Talk:Plasma (physics)/Archive 1

Archive 1

Archive 2

Shocks or double layers

This section is not scientifically sound, nor does it contain any references to support the claims of whoever wrote it. Please can someone change this?

"Plasma properties change rapidly (within a few Debye lengths) across a two-dimensional sheet in the presence of a (moving) shock or (stationary) double layer. Double layers involve localized charge separation, which causes a large potential difference across the layer, but does not generate an electric field outside the layer. Double layers separate adjacent plasma regions with different physical characteristics, and are often found in current carrying plasmas. They accelerate both ions and electrons." — Preceding unsigned comment added by 98.204.24.158 (talk) 13:45, 18 March 2012 (UTC)

Railgun

According to the Wikipedia article on railguns and its corresponding Talk page, a railgun is an example of artificial plasma generation and possibly application. Could this be added to a section (for example, Common artificial plasma or Examples of industrial/commercial plasma)? Occamsrazorwit (talk) 14:44, 2 November 2009 (UTC)

Keep Wikipedia G-Rated

The picture showm on the page is a shame!--205.215.119.34 (talk) 14:14, 10 September 2008 (UTC)

A plasma ball? 64.231.108.31 (talk) 16:37, 5 April 2009 (UTC)

Plasma Screen TVs

Do these types of TVs produce real plasma? how do they stop it from blowing up like a fusion bomb?

It would have to undergo the process of either nuclear fission or nuclear fusion, which would be impossible for a plasma TV, as plasma TVs don't actually use or produce any type of plasma. → JarlaxleArtemis 05:58, Jun 19, 2005 (UTC)

It's my understanding that plasma TVs do use plasmas of noble gases, hence the name. (See e.g. Plasma display.) They certainly do not cause nuclear fission or fusion reactions, which generally require extremely high temperature or pressure. Noble gases are used to avoid unwanted chemical reactions, which can easily occur under more reasonable conditions. Plasmas aren't necessarily all that hot, especially if they occur at low pressure.-- Beland 08:52, 10 July 2005 (UTC)

(??should these.......??)

(??should these broad fields be broken down here or in separate links - and if in separate links, ho so because the naming is broad and fairly arbitrary??) (?? I'd say leave the broad picture here then tree out from here on subpages. e.g. as I did Plasma Sources. RBYII ??) --Anon

Units

The equation shows 'cm' and very large powers of 10. Can somebody revise the equations to show 'm'? Bobblewik  (talk) 11:23, 28 Apr 2005 (UTC)

It's not necessary, as 1 cm = 100 m. → JarlaxleArtemis 06:00, Jun 19, 2005 (UTC)

1 m = 100 cm. And no, it's not necessary. You could write those equations with picometres, terametres, zeptometres or exametres (or worse, gigafeet) if you like. But it's common to use only SI base units in combination with scientific notation. The very purpose of scientific notation is to avoid difficult prefixes, so using them here is pointless and confusing. – Boudewijn 1 July 2005 12:34 (UTC)

Table

I think Iantresman's contribution (Characteristics table, plasma vs gas) is a good idea because it is not always clear why a plasma is special enough to be called a distinct phase of matter, but I am not entirely happy with the content. To begin with, it should be emphasized that all the differences mentioned (except "complex properties") are the result of a single difference, the electrical conductivity. Most of the "complex properties" arise from the presence of multiple species that are distinguished by their electrical charge (and in some cases mass). Finally, the electrical charge provides a means to influence the particle velocities directly, not just through collisions, leading to non-Maxwellian distributions and associated phenomena.

Some specific comments:

Electrical Conductivity

Very low Acts as a dielectric or insulator

Near perfect Supports electric currents that can spark or arc; in space plasmas, they are often called Birkeland currents. Such electric currents enable energy to be transferred 'invisibly' from one plasma region to another.

What is a Birkeland current? Currents do not necessarily transfer energy and energy transfer does not require currents.

Duality

None

Yes: passive and active plasmas As soon as an electric current passes through a passive plasma, it becomes active and exhibits more complicated features. In magnetohydrodynamics (MHD), it is practical to ignore the current (representing it as curl B); but as Nobel prize-winner for his work in MHD, Hannes Alfven, points out: "this method is unacceptable in the treatment of a number of [plasma] phenomena .. which require that the electric current is taken account of explicitly" (his emphasis).

Is this standard terminology (in astrophysics)? "Duality" is misleading. What, exactly, was Alfvén talking about?

Complex properties

None

Active plasmas may also exhibit: Noise (i.e., oscillations within a large frequency band) Non-Maxwellian energy distribution (i.e., not smooth) An electron temperature orders of magnitude greater than the ion temperature, which may be much higher than the neutral gas temperature At large current densities, may contract into filaments, sometimes called magnetic ropes or plasma cables, (as seen in lightning, aurora and nebulae) Can separate component gas mixtures in partially ionized gases Can produce double layers, the boundary between adjacent plasmas regions with different physical characteristics, that can explode, facilitate charge separation, and accelerate ions and produce synchotron radiation (such as x-rays and gamma rays) Can produce instabilities, which are identified by their distinct morphology (shape)

A smooth velocity distribution can also be non-Maxwellian. What does "separate component gas mixtures" mean? How can a double layer explode? A double layer does not facilitate charge separation, it is charge separation. What is meant by the "shape" of an instability? The Rayleigh-Taylor instability also exists in neutral gases.

There are a number of minor problems with the content and formulation as well. This table is a good start, but I think it needs a lot of work. Before I start it would help to have some answers to the questions above. Art Carlson 07:59, 2005 Jun 9 (UTC)

Ian Tresman writes:

I was a little surprised to find that someone had removed the table in its entirety, rather than simply moving it to another location.

You have some good questions, and thanks for pointing out my lack of understanding of non-Maxwellian, etc. I wonder whether some of these definitions should be answered with their own separate entries? I would certainly like to expand on Double Layers, for example. I'll add some clarification too. Ian Tresman 14:40, 2005 Jun 10 (GMT)

I didn't remove the table, I moved it to its own section (while editing it substantially).

• Duality: In the wave-particle duality there are two equal aspects of quantum behavior that must both be taken into account to understand some phenomena. In contrast, if you have a model that describes a plasma with current, then you can use also use it to describe a plasma without current simply by setting j = 0. Besides, current is not the real issue. There are many phenomena involving currents that can be described perfectly well within MHD.
• Non-Maxwellian: "Uneven" isn't any more helpful than "not smooth". Why not just "non-Maxwellian" with a link to Maxwell-Boltzmann distribution?
• Double layers: Do you really need a current to produce a double layer? Won't you get a double layer at any boundary between two plasmas with different temperatures? A separate entry for this topic is probably a good idea.
• Instabilities: Like I said, neutral gases also show a number of instabilities (Rayleigh-Taylor instability, Kelvin-Helmholtz instability, Baroclinic instability), so this is not a distinguishing characteristic.

Art Carlson 13:02, 2005 Jun 11 (UTC)

Thanks for your input:

• I don't want to compare plasmas to wave-particle duality, but to the fact that plasmas exhibit a wave aspect (that can be modelled with MHD), and a particle aspect (when an electric current passes through it, and MHD fails.) Sure, the electric current can be neglected in many models (especially when dealing with MHD and waves). But as soon as you get for example filamentation and double layers, then the electric current must be taken explicitly into account.

That sounds likes what I would call a fluid description as opposed to a kinetic description. Let's leave quantum mechanics out of it. For the third time, MHD does not automatically fail when current is present. Art Carlson 12:05, 2005 Jun 12 (UTC)

• We could link 'non-Maxwellian' to the Maxwell-Boltzmann distribution page, but it would be nice to express in a word or two, what this really means. In other words, how is it significant and what does it mean.

• True, double layers do not require a current, and are produced between any adjacent plasma regions with different properites.

Then what makes them explode? Art Carlson 12:05, 2005 Jun 12 (UTC)

• Plasma instabilities formed when an electric current flows through them can have their own characteristics. For example, fluids can produce a Kelvin-Helmholtz instability including plasmas; but pass an electic current through a plasma, and it can produce a diocotron instability which looks remarkably like a Kelvin-Helmholtz instability, but is produced in a different way and has unique characteristics.

Of course a plasma has different and more instabilities than a gas. But that fact would not normally be enough to classify it as a new phase of matter. Art Carlson 12:05, 2005 Jun 12 (UTC)

• If you want to have a go at tidying up the table/page, please go ahead. I can provide you with some addition information if you want to contact me by email, details at Ian Tresman 22:20, 2005 Jun 11 (GMT)

Please correct the Table "plasma scaling" "Density in particles per cubic metre" for "Terrestrial plasmas". In gases you already reach 10^19 particles per cubic cm what is 10^25 particles per cubic metre. The fusion plasma should reach an even higher density.

Complex Plasma Phenomena

I object.

• I have never heard the terms passive and active plasma applied to plasmas without and with current, and I can't find that use with Google. Can you back it up?

Alvén uses the terms in his book, Cosmic Plasma (p.37, 1981) when describing different kinds of plasma regions. Ian Tresman 00:50, 2005 Jun 24 (GMT)

I still don't think the term is either common or particularly helpful. Art Carlson 08:09, 2005 Jun 24 (UTC)

• The phenomena mentioned (Filamentation, Double layers, Birkeland currents, and Circuits) can all be described perfectly well with MHD.

My understanding is that MHD approximates these phenomena, and can misrepresent the particle aspect of the current. One again, this is from Cosmic Plasma. I believe Hall MHD is required for some conditions. Ian Tresman 00:50, 2005 Jun 24 (GMT)

Then you have to specify just what aspect is misrepresented. It's misleading or wrong as it is written. The place to discuss the limitations of a fluid theory is the section on "Mathematical descriptions". Art Carlson 08:09, 2005 Jun 24 (UTC)

• One of them (Double layers) doesn't have anything at all to do with current.

My understanding again is that double layers accelerates ions, hence there is a current? Ian Tresman 00:50, 2005 Jun 24 (GMT)

Not necessarily. It depends on what the electrons and the other ions are doing. An even so, it would be the double layer causing the current, not the current causing the double layer. Art Carlson 08:09, 2005 Jun 24 (UTC)

There may be a point worth making here, but I don't understand what it is, and the section as it stands is unacceptable. Art Carlson 20:37, 2005 Jun 23 (UTC)

If you contact me by email, I'll provide some more information. Ian Tresman 00:50, 2005 Jun 24 (GMT)

Don't you think the info would be useful to all editors of this page? Besides, you can email me here, but you haven't entered your address. Art Carlson 08:09, 2005 Jun 24 (UTC)

I can live with the version of 10:46, 2005 Jun 24, since you've sidestepped the issues of current and MHD. As a physicist I tend to start with equations of state and waves and linear instabilities, but the real world is non-linear, and it is worth pointing out the complex structures that plasmas can form. It may be that what you are trying to express is not kinetic effects as such but non-linear effects, which in many cases come from kinetics. Art Carlson 10:37, 2005 Jun 24 (UTC)

Crystalline non-neutral plasma

I think the phrase "Crystalline non-neutral plasma" in the plasma scaling table needs to be explained more. I'm at least moderately familliar with plasmas and science in general but I find the idea of a crystalline plasma nearly impossible to conceptualize. what IS it?? --Deglr6328 04:16, 5 September 2005 (UTC)

There's not much on the Web about it, is there? To begin with, "plasma crystal" can refer to an ordered array of macroscopic particles in a dusty plasma. These plasmas are neither non-neutral nor cold. That's not what is being refered to here. "Non-neutral plasmas" have just one species, usually electrons. They need to have a good confinement device, such as a Penning trap, and even then they can't contain very many particles before the electrostatic repulsion blows them apart. They have been studied for twenty some years, and the physics is fascinating, if academic. Since there is no recombination with a single species, the temperature can be reduced dramatically. Eventually the Coulomb force between neighbors forces a regular ordering - a crystal. Still, plasma phenomena like plasma oscillations and electric field screening exist. I hope that helps clear your head. Unfortunately, I don't think I know enough to write more than a stub about any of this. --Art Carlson 15:51, 16 September 2005 (UTC)

It does! I think. So, a cold trapped electron (or proton, I guess) cloud basically then? How do you cool an electron cloud though?!--Deglr6328 03:31, 29 September 2005 (UTC)

Not sure, but I think you could let a few cold gas atoms wander around. As long as the electrons are warm, they will lose energy by exciting the atoms, which then radiate. Once the electrons are reasonably cold, they will (slowly, because of the mass difference) lose energy through elastic collisons. You might be able to help things along with some cycles of adiabatic compression and expansion. --Art Carlson 08:59, 29 September 2005 (UTC)

99.999...

comprising more than 99% of the visible universe

Over 99.999% of the Solar System by volume is plasma.

Where do these numbers come from? By volume I hold them to be such underestimates that they are practically misleading, i.e. the solar system is actually closer to 99.99999999999999% plasma by volume. But the volume fraction, whether of the solar system or of the universe, is probably not a very meaningful measure for most purposes. (What is the purpose, anyway?) The concept of "visible universe" is also a bit of a weaselly term. Humph! --Art Carlson 14:20, 16 September 2005 (UTC)

It is indeed a weasily term however it's the most that can be said with reasonable validity. Stars are all plasma and all we see are stars but there is other stuff. dark matter seems to comprise about 90% of the universe and we have no idea what it is. Therefore if we reffered to percentage of the universe instead of percentage of the visible universe we'd have to say 10% and we have no clue about the other 90%. As for 99% being misleading, it does say over 99%. With how little we know about dark matter and black holes I'm satisfied with leaving it at 99% (or 99.99%). I'd rather be a little bit less exact then be wrong. If we say more than 99.9999999999999% and it ends up being 99.992% we could end up looking a little silly. Vicarious 00:05, 21 September 2005 (UTC)

Whether the numbers are 99.992% 99.99999999999999% or 99.999% these numbers are all more than 99%, leaving out dark matter if you will. It clearly states, "comprising More than 99% of the visible universe"....

I think a better way to phrase it to say of visible matter. Within the visible universe we assume (currently) that there is a lot of dark matter. —Preceding unsigned comment added by 209.6.125.212 (talk) 01:30, 12 September 2007 (UTC)

Some estimates suggest that up to 99% of matter in the entire visible universe is plasma. has always been a dorky sentence. I boldly tried to find a better formulation (including some changes in the footnote). Tell me what you think of it. --Art Carlson 08:44, 13 September 2007 (UTC)

Phases of matter

Are there any terms for change of state to/from plasma. For example solid to liquid is melting, gas to liquid is condensation. Is there a term for plasma to gas or anything else related to plasma? Vicarious 00:05, 21 September 2005 (UTC)

I usually say "the gas ionizes" and "the plasma recombines". Also "In semiconductor processing, ignition is the process of starting up a plasma generator." --Art Carlson 07:31, 21 September 2005 (UTC)

Sounds good to me, thanks. Follow up question, is it only possible to go to plasma from gas? It's undoubtedly the primary method but chemistry is full of exceptions. For example theres a term for sublimation when a solid goes to a gas skipping over liquid. My question is, is there a term for anything besides to/from gas, and if not is it not actually possible, or would it simply be referred to as ionizes even if it was solid to plasma?

Image: Large Helical Device

This image was just removed and then revered to return it. It was removed because the nearly 1mb file is too much for dial-up. I'm inclined to agree, especially because it's better suited in the Large Helical Device article then it is here and doesn't do much to clarify plasma in my mind. I'm gonna take it down and add a link to it.Vicarious 17:44, 22 September 2005 (UTC)

I think this image should be kept. It is the only image which strikingly demonstrates the effects of strong magnetic fields on a plasma (you can SEE it twisting) and also wiki is not intended to be designed around the needs of dialup users. There are many pages with animations far larger than this one.In any case the text loads before images so dialup users should not have a problem there anyway.--Deglr6328 23:51, 27 September 2005 (UTC)

Wikpedia does pander to users with lesser computers. For example Periodic table of elements contains Periodic table (standard) rather than Periodic table (large version), although this is primarily an issue of screen size, not bandwidth it still addresses the same point. I'd encourage you to add a better link then the see also section though, perhaps in an empty image box with a link to the actual image. Also a sentence (possibly a caption to the non image) explaining it's pertinence to plasma. I think it's nifty but it's most nifty on a page for manetic fields or for large helical devices, seing a flash of purple doesn't help me understand plasma without a descriptive caption. Vicarious 00:33, 28 September 2005 (UTC)

I asked at Wikipedia_talk:Image_use_policy#Policy_on_large_animations after reverting, but no response. — Omegatron 13:41, 29 September 2005 (UTC)

I liked something Omegatron mentioned at the policy page, what if we add a still of the animation and in the caption link to the animation, it seems like a good compromise. Vicarious 15:29, 29 September 2005 (UTC)

Agree.--Deglr6328 21:47, 30 September 2005 (UTC)

Added to policy. ··gracefool |☺ 22:23, 30 September 2005 (UTC)

Re "Wikpedia does pander to users with lesser computers" - it's not pandering, it's simply accessibility. Wikipedia aims to be accessible to as many people as possible. For instance, articles are designed to be just as readable for people who turn off images (for whatever reason, whether preference or because they are blind). ··gracefool |☺ 22:07, 30 September 2005 (UTC)

No offense intended, just trying to get the idea accross, your terminology was better then mine. Vicarious 01:45, 1 October 2005 (UTC)

So, um, now that we decided what to do I think this is staring contest part where we wait for each other to make the smaller non animated version and post it. I'd like to be the first to immaturely yell "not it". ;-) Vicarious 01:44, 1 October 2005 (UTC)

Haha. So no one ever did this? — Omegatron 03:29, 22 December 2005 (UTC)

Fire = plasma ?

An edit was recently made to the Fire article removing the statement that it is a form of plasma, edit was annotated: "Flames aren't usually considered plasma; they're commonly not ionized much if at all." (made by Atlant)

If this is true, the candle image here should be removed and perhaps a small note added to the body of the article explaining that fire is sometimes thought of as a plasma but actually isn't. --Bk0 23:11, 14 October 2005 (UTC)

I (a plasma physicist) always thought a flame was a plasma. Now that you mention it, I don't know what the degree of ionization of a flame typically is. I found a couple indications, though, that a flame can conduct electricity and therefore must be a plasma:

• http://www.soteria.com/brown/docs/ehydro/speaker2.htm under "Flame Ionization", and
• http://www.madsci.org/posts/archives/feb98/888372043.Ot.r.html

--Art Carlson 11:11, 15 October 2005 (UTC)

Thank you. --Bk0 17:50, 15 October 2005 (UTC)

I discovered some conflicting information from a NASA FAQ saying that not all flames are plasma, as "To create a plasma takes more energy, and requires a higher temperature than the flame provides. The collisions between atoms need to be energetic enough to kick an electron completely out of the atom."

http://www-spof.gsfc.nasa.gov/Education/FAQs7.html#q97 Author and Curator: Dr. David P. Stern (http://www-spof.gsfc.nasa.gov/Education/wstern.html)

I'm not saying that flames cannot produce plasma, but this article currently states "All fire" is plasma, which could be false if this assessment is correct.

Ldhotsoup (talk) 16:53, 5 February 2010 (UTC)

I'm not a plasma specialist, but my experience tells that hot flames could well be plasma (various CVD methods where significant ionization is required) or could be not (phosphorus reaction with oxygen [1]). Thus I'm going to change statements like "all flames are plasma" Materialscientist (talk) 01:58, 6 February 2010 (UTC)

Requested move

Plasma redirects here, so it would remove the unneccesary clarifier.—jiy (talk) 20:33, 26 November 2005 (UTC)

---

Add *Support or *Oppose followed by an optional one sentence explanation, then sign your vote with ~~~~

• Support—jiy (talk) 20:33, 26 November 2005 (UTC)
• Oppose Blood plasma, Plasma display, Plasma television and Plasma cutter exist on Wikipedia - we probably should have a disambiguation page. DV8 2XL 20:43, 26 November 2005 (UTC)
  • Comment Huh? There is a disambiguation page, see Plasma (disambiguation).—jiy (talk) 20:57, 26 November 2005 (UTC)
    • Comment Since that is the happy case then shouldn't Plasma redirect there and be done with it?
      • Comment No. The Plasma display, Plasma television, and Plasma cutter you listed all refer to the plasma being described in this article, which is some indication that the plasma in the physics sense is the main use of the term. Check out the what links here for plasma for more evidence.—jiy (talk) 21:21, 26 November 2005 (UTC)
        • Comment OK, lose those links they don't have to be involved, however the ones listed on Plasma (disambiguation) still need to be accounted for and other disciplines use the term plasma in other ways than does physics. DV8 2XL 21:35, 26 November 2005 (UTC)
          • They are accounted for. Moving Plasma (physics) to Plasma (which redirects to Plasma (physics) anyways) wouldn't suddenly make Plasma (disambiguation) disappear. If you notice, there is a link to Plasma (disambiguation) at the top of Plasma (physics) so if a user is looking for a different term, they can find it. This is standard practice; for instance, see Tree and Blood.—jiy (talk) 22:42, 26 November 2005 (UTC)
• Support—Wechselstrom 03:23, 27 November 2005 (UTC)
• Oppose (but I would support moving Plasma (disambiguation) to Plasma). — Knowledge Seeker দ 03:55, 27 November 2005 (UTC)
• Oppose Agree with Knowledge Seeker, this should be the disambiguation page. "Plasma" has a long history of usage before it was applied to this phenomenon. Jooler 04:30, 27 November 2005 (UTC)
• Support. History of usage has little to do with it. This meaning is more likely to be used without adjective or other qualification, and many of the links to blood plasma come from redirects from [[serum]]. Gene Nygaard 17:41, 27 November 2005 (UTC)
  • Comment A somewhat POV statement as I suspect there are as many health-care workers that use the term to mean a component of blood, as those that use it in the present sense. DV8 2XL 17:49, 27 November 2005 (UTC)
• Oppose. Plasma should be a disambiguation page. --Bk0 (Talk) 19:39, 27 November 2005 (UTC)
• Comment "Plasma" should point to this page (directly or redirectly) because it is the "primary meaning" (see Disambiguation#Page naming), as evidenced by "What links here". I don't see any difference whether this page is called "Plasma", "Plasma (physics)", or "Plasma physics". The note at the top of the page mentions blood plasma specifically because it is clearly the second most important meaning, so any medical students losing their way can quickly get to where they want to be. --Art Carlson 20:30, 27 November 2005 (UTC)
  • COMMENT plasma (physics) and plasma physics should be two separate articles. 132.205.46.170 23:35, 28 November 2005 (UTC)
• OPPOSE, plasma should be a dab page. Plasma in the physics meaning is not clearly the primary meaning. Talk to a medical doctor for instance (there are more of those than physicists anyways). 132.205.46.170 23:34, 28 November 2005 (UTC)

Agreed. Just recently on my local news broadcast they used the word "plasma" as shorthand for plasma TVs ("Thinking of getting a plasma this Christmas? They aren't all the same...", etc). Visitors searching for "plasma" should first reach a disambig page, rather than this article which they may find bewildering. --Bk0 (Talk) 00:17, 29 November 2005 (UTC)

Just because the standards of your local TV station are so poor is not a justification to mess up an Encylopedia. Why not suggest that they get a fact checker on their staff? Vegaswikian 03:44, 30 November 2005 (UTC)

• Support. Most users who are looking for Plasma will want this article. The DAB pointer addresses the few who arrive here incorrectly. Vegaswikian 03:40, 30 November 2005 (UTC)

Discussion

Add any additional comments

This is all wrong Plasma should be a disambiguation page. Jooler 04:30, 27 November 2005 (UTC)

• This is a courtesy notice that I have suggested that Plasma (disambiguation) be moved back to Plasma. The former was created by a cut-and-paste move from the latter, which was then changed to redirect here. — Knowledge Seeker দ 04:46, 30 November 2005 (UTC)
• This is the page, I was looking for, but Plasma (disambiguation) was helpful in my understanding of what plasma means to other people. More numbers would help ie is low voltage 15 pico volts or 15 volts? The latter in ignatrons, electric arc welding and thyratrons, about 100 volts in florescent tubes including compact florescents, I think. The article is appropiate in most respects, but needs occasional explanations directed to the novice. It is appropriate to use both prefixes and powers of ten. Understanding of the latter is decreasing now that slide rules are obsolete. Most dictionaries do not specify powers of ten as a meaning of orders of magnetude = OOM. In my opinion OOM is inappropriate unless the power of what is specified, as astronomers do for the brightness of stars. For star brightness, 6 orders of magnetude = a brightness change of 100 times not one million times. Neil Ccpoodle 22:59, 4 April 2007 (UTC)

Ionized

"Ionized" in this case means that at least one electron has been removed from a significant fraction of the molecules.

Makes it sound like the plasma is a group of positively charged molecules with the electrons removed from the plasma as a whole. Does the plasma have a positive charge or are the electrons floating around in there, too?

The electric arc in an arc lamp or an arc welder

The arc itself isn't plasma, is it? The arc is creating and travelling through the plasma. Likewise with other examples. — Omegatron 01:50, 8 December 2005 (UTC)

Perhaps "dissociated" is a better word re: the electrons? A diagram could help, too. --Bk0 (Talk) 02:24, 8 December 2005 (UTC)

Plasma engines

With the recent sucessful tests by the ESA on plasma engines [2], should a page be made for them? Oberiko 13:47, 15 December 2005 (UTC)

Page moves

I am posting here because I noticed that this page appeared to be a partially completed page move request. Currently, Plasma (physics) redirects to Plasma, but Talk:Plasma (physics) does not redirect to Talk:Plasma. There is also the issue of Plasma (disambiguation) being moved to Plasma. When consensus has been reached on what should be done regarding these articles, please let me know, and I will be more than happy to complete the move request. I am cross-posting this to Talk:Plasma (disambiguation) as I am unsure which set of articles are being actively monitored. Thank you! --HappyCamper 21:07, 25 December 2005 (UTC)

Thanks for your comment, HappyCamper. As one who has been active in the discussions, I am not a disinterested editor, but here is my interpretation of a slightly complex situation:

• On May 3, 2005, a user (without discussion?) copied-and-pasted Plasma (a disambiguation page) to Plasma (disambiguation), then changed the former to redirect to Plasma (physics). The new disambiguation page now has a history as well.
• On November 26, 2005, a user noticed the redirect from Plasma to Plasma (physics) and proposed the later be moved to the former. Again I am not unbiased, but with four votes supporting the move and five against (including an anonymous voter), the requested move clearly did not achieve consensus.
• On November 30, 2005, I proposed moving Plasma (disambiguation) to Plasma. I soon discovered the cut-and-paste move and amended my request. Notices were placed on Talk:Plasma (disambiguation), Talk:Plasma (which had not been moved during the May 3 cut-and-paste), and here on Talk:Plasma (physics) as well.
• The move I proposed to undo the cut-and-paste received two supports (aside from me) and no opposition.
• Today, an administrator, perhaps unaware of the active move requests, deleted Plasma (with 119 edits) without comment. He then moved Plasma (physics) there (leaving the talk page behind), and again left no explanation.
• I saw your comments, discovered the out-of-process actions, and undid both the move and undeleted Plasma.

My summary would be that the proposed move from Plasma (physics) to Plasma failed to achieve consensus. The proposed move from Plasma (disambiguation) to Plasma did, although there was a low turnout, especially as it was performed without discussion. Obviously, I feel that Plasma (disambiguation) should be moved back to Plasma, but I will leave the interpretation up to you. If you decide to do so, you will have to merge the histories, since the current disambiguation page was created by cut-and-paste. Thank you. — Knowledge Seeker দ 23:38, 25 December 2005 (UTC)

Well, I did my best :-) Both the article history and the talk pages needed to be fixed. That was quite tricky! I am going to remove the move request now. --HappyCamper 21:32, 26 December 2005 (UTC)

?!

What is going on here?! In case you haven't noticed, virtually the entire article is now missing! I will revert all recent edits to the dec. 24 version if the above parties involved in recent moves don't fix it.--Deglr6328 07:18, 27 December 2005 (UTC)

Sorry about that—I don't know what happened there. A user had cut-and-pasted one of the articles which made things a bit complex, although I'm not sure how that affected this article. In any case, I reverted the last edit which seems to have fixed matters. Please let me know if I'm correct or fix it if you can. Thanks! — Knowledge Seeker দ 07:46, 27 December 2005 (UTC)

looks ok now.--Deglr6328 08:34, 27 December 2005 (UTC)

Plasma /beta parameter

The 'DIII-D (fusion reactor)' article refers to 'plasma \beta parameter', and this reference is wikified to 'Plasma (physics). However, I cannot see a 'Plasma \beta parameter' in this article.

Please clarify to what the 'DIII-D (fusion reactor)' could be referring to.

Duncan.france 22:44, 16 January 2006 (UTC)

OK. I think I have found it : 'thermal/magnetic energy ratio'. Is that right?

If so, perhaps the 'DIII-D (fusion reactor)' article should be modified accordingly...

Yeah, that's it, but you do call it \beta. In the context of a tokamak device, \beta is the "quality" of the magnetic confinement. The full equation would be roughly (3/2)nkT / (1/2 \mu_0 B^2), which is the thermal energy of the plasma divided by the energy contained in the magnetic field. The value is typically a few percent.

The link should probably point to tokamak, because the DIII-D is/was a tokamak. - mako 05:06, 17 January 2006 (UTC)

Electromagnetic vs gravitational forces

My mistake over EM always dominating gravitation forces for charged particles in a plasma. I think I'm trying to explain the statement in "Dynamics" at Dusty plasmas. --Iantresman 23:15, 21 March 2006 (UTC)

Fundamental plasma parameters

I'm wondering whether the Fundamental plasma parameters should be removed to an article of their own. I must admit that they mean very little to me, and I think that an article of its own would allow room to explain what each one means? --Iantresman 09:45, 24 March 2006 (UTC)

You're right that this section is more technical than the rest — probably too much for the average reader. The reason they are not all explained now is not because of space limitations but because no one has had the knowledge, time and willingness to expand them. The article is already very long, so I wouldn't object if you moved that section to its own page. --Art Carlson 10:36, 24 March 2006 (UTC)

Double layers and synchrotron radiation

I notice that the information on double layers producing synchrotron radiation has been removed. References seem to support that double layers will accelerate electrons through pinches that will indeed produce synchrotron radiation:

• "A very interesting astrophysical application of double layers which was discussed was in connection with extragalactic jets. It was shown that strong plasma double layers can exist within self-maintained density cavities. These double layers will emit relativistic electrons which, in turn, will produce synchrotron radiation making the plasmas in the immediate locality radio luminous." [3]
• "Where double layers form in the pinches, strong electric fields can accelerate the charged particles to high energies, including gamma ray energies (Alfven, 1981). These should then display the characteristics of relativistic charged particle beams in laboratory surroundings, for example, the production of microwaves, synchrotron radiation, and non-linear behavior such as periodicities and 'flickering.'" [4]
• "Double layers produce beams of electrons and, on astrophysical scales, these beams are relativistic. The beams are also directed along Bo so that the expected loss mechanism for the beam kinetic energy is synchrotron radiation." Anthony L. Peratt, Physics of the Plasma Universe (1992)
• "An acceleration mechanism that was first advanced to account for astrophysical phenomena (mainly, acceleration of cosmic ray particles and relativistic electrons in synchrotron jets), is briefly reviewed, and it is shown that a similar mechanism can account for acceleration in the plasma focus. In the plasma focus, current flows through annular channels are defined by radial double layers. " [5]
• "When electrons conducting the currents outside the double layer reach the double layer, they are accelerated to very high energies. Similarly, ions reaching the double layer on their outward motion from the central galaxy, will be accelerated outwards when passing the double layers. The strong axial current produces a magnetic field, which pinches the plasma, confining it to a cylinder close to the axis. Although the electrons are primarily accelerated in the direction of the magnetic field, they will be scattered by magnetic inhomogeneities and spiral in such a way that they emit synchrotron radiation", Hannes Alfvén, Cosmic Plasma (1981).

--Iantresman 12:03, 30 March 2006 (UTC)

I removed that, because double layers produce beams of charged particles and inside the DL there is "linear acceleration emission". The production of synchrotron radiation has nothing specifically to do with DLs. Any accelerated partice in a magnetic field, even a homogeneous magnetic field, will usually have a component of its velocity perpendicular to the magnetic field and will therefore rotate around it. It will emit cyclotron radiation in case the particle velocity is not relativistic and it will emit synchrotron radiation if it has been accelerated to relativistic velocities. It is nice what alven writes, but there is no reason not to assume that the electrons and ions already spiral around the magnetic field before entering a DL. Peratt quote is very misleading, because if the beams are purely directed along B0 then there will be no synchrotron radiation. He is very poorly expressing himself.--Tusenfem 08:48, 31 March 2006 (UTC)

So are we suggesting that the double layer itself does not produce the synchrotron radiation, that there are no plasma-related mechanisms that produce synchrotron radiation, or that some other aspect of plasma may produce synchrotron radiation (eg. double layer accelerated electrons moving through a pinch)? --Iantresman 09:57, 31 March 2006 (UTC)

Well, I am suggesting that (i.e. the first thingy), dunno who the "we" is. A double layer is just a means to get accelerated electrons and ions. The charged particles are accelerated along the electric field. Now, it may be possible that they gyrate around the magnetic field, and they will emit cyclotron/synchrotron radiation. Take a look at a general physics book, for goodness sake, and look up synchrotron radiation. It is created by relativistic charged particles taht gyrate around a magnetic field. From Rybicky and Lightmann "radiation processes in astrophysics" (one of the best books I think on this topic) chapter 6: [i]Particles accelerated by a magnetic field B will radiate. For non-relativistic velocities the complete nature of the radiation is reather simple and is called[/i] [b]cyclotron radiation.[/b] [i]The frequency of emission is simply the frequency of gyration in the magnetic field. However, for extreme relativistic particles the frequency spectrum is much more complex and can extend to many times the gyration frequency. This radiation is called[/i] [b]synchrotron radiation.[/b]. All one needs is a relativistic particle in a B field to get synchrotron radiation. A DL can be the cause that there are relativistic particles. It is A creates B and B creates C, but that does not mean that A creates C. Only relativistic DLs will create relativistic particles which can create synchrotron radiation. Any other DL will not. --Tusenfem 12:02, 31 March 2006 (UTC)

Temperature

The defining characteristic of a plasma is ionization. Although ionization can be caused by UV radiation, energetic particles, or strong electric fields (processes that tend to result in a non-Maxwellian electron distribution function), it is more commonly caused by heating the electrons in such a way that they are close to thermal equilibrium so the electron temperature is relatively well-defined. Because the large mass of the ions relative to the electrons hinders energy transfer, it is possible for the ion temperature to be very different from (usually lower than) the electron temperature.

I see a problem here in the first few sentences. First it is said that the ionization can be caused by ... but more commonly caused by heating. I think the sentence stop there. What comes behind has noting to do with ionization, there the paragraph enters into the temperature domain. One does not just heat the electrons, one heats the whole gas, which in the end, because of collisions etc. will give electrons enough energy to escape the nucleus. For the temperature, there is exchange of energy between the electons and between the ions, but not inbetwixt because of the greater mass of the ions. To thermal equilibrium is reached by the electrons and by the ions at different tempreratures.--Tusenfem 12:55, 4 April 2006 (UTC)

If only a small fraction of the gas molecules are ionized (for example 1%), then the plasma is said to be a cold plasma, even though the electron temperature is typically several thousand degrees.

Unfortunately, this is wrong. A plasma is not called cold because it has a low ionization degree, but when each species has only one energy, i.e. all electrons have one velocity and all ions have one velocity, there is no spread in velocity space. Naturally, this means that also the definition of a hot plasma is wrong.--Tusenfem 12:58, 4 April 2006 (UTC)

Because the plasmas utilized in plasma technology are typically cold, they are sometimes called technological plasmas. They are often created by using a very high electric field to accelerate electrons, which then ionize the atoms. The electric field is either capacitively or inductively coupled into the gas by means of a plasma source, e.g. microwaves. Common applications of cold plasmas include plasma-enhanced chemical vapor deposition, plasma ion doping, and reactive ion etching.

This needs to be rewritten, as it is not very clear. a microwave is not a plasma source, but is used in a plasma source. Also, again the cold thing here, it may be correct that 'technological plasmas' are cold, I don't know, it is not my field of expertise. And the electric field being capacitively or inductively coupled to the gas does not make sense. Inductively you would create a current with a magnetic field. I hope someone with expertise in technological plasmas can change this.--Tusenfem 13:05, 4 April 2006 (UTC)

Can you come up with a better definition for cold and hot plasmas, that people will understand. I think I also read somewhere that the electrons in a cold plasma do not have enough energy to move out of the ions's debye sphere, and that a low ionoized gas typified a cold plasma? --Iantresman 14:17, 7 April 2006 (UTC)

The definition of a cold plasma is that the electrons (ions) have a very small temperature spread. A temperature is given by a distribution function that peaks at a certain temperature, comparable with a Gaussian distribution. Now, imagine that in this Gaussian distribution the width goes to zero. Then you get a delta function, all electrons (ions) have the same "temperature". Naturally, a temperature is a moment of the particle distribution function, so what this means is that all electrond (ions) move with the same velocity.

So definition: A cold plasma is a plasma in which all electrons (ions) basically move with the same velocity, there is no spread. In physical terms, this means that the particle distribution function can be seen as a delta function in velocity space. Contrary to expectations, a cold plasma can have a very high temperature, assuming that the temperature is given by $T_{e,i}=0.5m_{e,i}v_{e,i}^{2}/k_{Boltzmann}$.

I have never seen the definition that you wrote down about electrons not being able to move out of the ion's DeBye sphere. Through Saha's equation you can see that low temperature plasmas will have a smaller ionization grade. But low-temperature cannot be set equal to cold, in plasma physical terms.

Naturally, I am willing to rewrite the section about temperature. Cheers, Martin --Tusenfem 16:49, 8 April 2006 (UTC)

That explanation is very confused. Electrons have a distribution of velocities, not of temperatures. The temperature (if it is definable at all) is found from the width (spread) of the velocity distribution. It is possible, but practically never the case, that the mean electron velocity is greater than the thermal velocity. These things may muddy the water, but they are not the problem here. Obviously a plamsa with T = 0 is cold; the question is, how warm can a plasma be and still be considered cold? The answer I gave, and to which I stand, is that the biggest change is properties as a plasma goes from very cold to very hot, is when the degree of ionization approaches unity. This makes double sense because the Saha equation tells us that the ionization depends sensitively on the temperature and hardly on anything else.

I can't make any sense out of the Debye sphere business.

I do not like the section "Types of plasma" at all. They are not "types", the section mixes categories that have little in common, and most of the topics belong more naturally in a different section.

--Art Carlson 08:41, 9 April 2006 (UTC)

Art! I think that is what I wrote, that the electrons have a spread in velocity. In plasma physics you will find the so called cold-plasma approach, in which it is assumed that all electrons or ions have the same "temperature", meaning that there is no thermal spread in the velocity distribution function, each species is described by charge, mass number density and velocity, and thermal motion is neglected. See e.g. Don Melrose's book Instabilities in space and laboratory plasmas chapter 2.

Naturally, if you like, you can determine cold-warm-hot with respect to temperature, but what sets the limit? Is a plasma cold if it has less the say 1% of ions? AFAIK in my field of research a cold plasma is as defined in the few sentences above. --Tusenfem 11:49, 10 April 2006 (UTC)

I'm sure you think that you wrote that, but it's not what you actually wrote. A single electron does not have a temperature, so it doesn't make any sense to say that "all electrons have the same temperature".

Again, there is no question that a plasma is cold when T=0. The question is how high T can be before you can no longer treat the plasma as if T=0. I insist that a common and useful distinction is the degree of ionization. Do you have a problem with including that in the article?

There can well be other distinctions. For example when considering plasma oscillations, a plasma is "warm" when the spatial scale of the problem is smaller than the Debye length. We could expand the explanation of "warm" and "cold" plasmas in different contexts, but it is not enough to draw the line at T=0.

--Art Carlson 12:43, 10 April 2006 (UTC)

I think that related to this, is that sometimes there are formal and informal definitions, and the latter is often more informative to the non-scientists. For example, I recalled that by formal definition, a plasma is defined by the "plasma approximation" having a certain value? But informally, it is an ionized gas.

So I wonder whether "cold plasma" has formal and informal definitions? I suspect that there is a relationship to the degree of ionization, but it does not define it?

Here are some definitions of cold plasmas that I have found in the literature:

• "The cold plasma model assumes in fact, a zero plasma temperature..." (Fundamentals of Plasma Physics by J A Bittencourt) [6]
• "We assume that there are not any random motions. This idealised system is referred to as a cold plasma. The particle function of a cold plasma is a [delta]-function centred on the average velocity". (An Introduction to Plasma Astrophysics and Magnetohydrodynamics by Marcel Goossens) [7]
• "A cold plasma is one whose particle energies are small enough that electromagnetic forces contrain the plasma to move with the magnetic field' A hot plasma is energetic enough to escape such constraints." (Neptune by Ellis D Miner, Randii R Wessen) [8]
• "By a cold plasma, we mean one in which the electr temperature may be neglected and ion motion is unimportant" (he Solar Corona by Leon Golub, Jay M. Pasachoff) [9]
• "In a cold plasma, where the charge carriers oscillate about fixed positions, T=0 . In a hot plasma, bodily transport of density, velocity, and energy fluctuations by the free-streaming particles lead to finite values for T." (Anthony L . Peratt, Physics of the Plasma Universe)

--Iantresman 13:35, 10 April 2006 (UTC)

Okay, we'll just leave it as it is, although it is fairly common to give an electron a temperature with the relationship I gave above. Just make clear that you use the Saha equation to define cold-warm-hot and try to come up with good values.

I didn't really like the section on temperature as it was: temperature is (roughly) defined in terms of free energy per degree of freedom, and measured in Kelvin and eV, and this is the most important thing to start with. Ionisation is dependent mostly on temperature, sure, but we shouldn't start a section on temperature by talking about ionisation, as the definitions of hot and cold are secondary considerations compared to the meaning of temperature itself. So I have reordered it, and removed some material which could better be placed elsewhere. To fit it in with the flow of the section, I have also added the plasma characteristic, 'Degree of ionization'.

--Dashpool 18:00, 27 April 2006 (UTC)

Could some distinction be made between thermal and nonthermal plasma in this section? --212.108.17.165 10:39, 29 August 2006 (UTC)

Good show, good article!

Contratualations to the editors who have contributed to this article, it seems that we have now acquired "Good article" status. Maybe the article is now on its way towards Featured article status.

I still think there is room for improvement, probably starting with a better categorisation of section. --Iantresman 07:40, 7 April 2006 (UTC)

Types of plasma

I've expanded the section on Ultracold plasma to be one on "types of plasma", since we don't really discuss them together. I wonder whether the section on Common plasma would make a good introduction to this section, and the whole section moved to where Common plasmas is now? The section on Characterists seems a bit more technical, and have lesser appeal, and perhaps should come afterwards? Ideally we should mention some of the characteristics in the section on type, in order to warm the reader to them? --Iantresman 22:29, 7 April 2006 (UTC)

J.J. Thomson

In keeping with the wikipedia suggestion to be bold, I have changed (Sir) Joseph John (J. J.) Thomson, to Sir J. J. Thomson. In my estimation, J. J. Thomson is more well known, and the initials may be found out by following the link. The reason for including Thomson's title the link is it matches the link to Sir William Crookes. Forgive me if this issue has already been dealt with and settled. -Fermion 06:41, 19 April 2006 (UTC)

plasma parameter

1. Shouldn't the number of particles in a Debye sphere be (4pi/3)*n*lambda_D^3 (instead of (4pi)...)?
2. Is there a deeper connection between the use of Lambda to denote the number of particles in a Debye sphere and the use of Lambda to denote the ratio of the maximum to minimum effective impact parameter (as in lambda = ln(Lambda), see Coulomb collision? Or is it just notational double-duty?

--Art Carlson 10:12, 17 May 2006 (UTC)

• I've corrected the Debye sphere calculation, though I'm still not entirely sure what factor "defines" a plasma as a plasma. On the one hand, Λ<<1 is the plasma approximation, but Λ>>1 is a "Weakly coupled plasma".
• The text also says that "This second criterion can be expressed as Λ>>1"; but I'm not sure what is the "first criterion" as three points are shown? --Iantresman 13:08, 22 June 2006 (UTC)

• ...and answering my own question, it refers to the second of three criterion specified. --Iantresman 13:23, 22 June 2006 (UTC)

Deglr6328

Better people than you or I have judged Peratt's work to be worthy of publication in, for example, Astrophysics and Space Science,[10], and The Astronomical Journal,[11]. I suggest that you write them a letter and tell them how nutty you think his work is.[12]

Incidentally, Peratt's book contains nothing about cosmology... hence it's title, Physics of the Plasma Universe. --Iantresman 00:19, 4 July 2006 (UTC)

sorry, not buying it, sell it to someone else. and as long as we're airing grievances, I frequently find your edits to be intellectually dishonest in the extreme. --Deglr6328 00:52, 4 July 2006 (UTC)

It's not for you to buy, or judge; What you or I think of plasma cosmology is not worth a fig. Not that plasma cosmology has anything to do with plasma physics... except perhaps that a plasma cosmologist, Hannes Alfvén has contributed more to astrophysical plasmas than most.

As for intellectual dishonesty, it is ironic that someone who claims to have "little patience for pseudoscience"[13] has to resort to "attacking the motives or character of anyone..", a characteristic found in the section on "Identifying pseudoscience"[14] --Iantresman 09:06, 4 July 2006 (UTC)

Plasma filaments in nebulae

Art, what am I missing regarding plasma filaments in nebulae? I concede there is no proof that nebulae contain filaments due to any specific cause, (ie. they must be theory/hypothesis), etc. But the following all have the characteristics of plasma filaments, and are recognised by the authors as plasma filaments:

• Graham, et al, note that regarding the Crab nebula, "... the current density in the filaments is too low for significant molecule formation.." (last para.)[15].
• Münch on the Crab Nebula notes "... the filaments move in a force-free field, in which the current density j, is parallel to the magnetic field strength,..." (top right column)[16].
• And doesn't Hardee mention in regard to the Crab nebula that "the plasma forms quasi-stationary self-pinched current filaments",[17] not because of a random theory, but because (a) filaments are seen,[18] (b) they can also can explain the infrared, optical, X-ray, and gamma-ray pulsed emissions.

I realise that just having the characteristics of a plasma filament does not make something a plasma filament. But isn't like arguing that just because it has the characteristics of dark matter, it does not make it dark matter because it is not "seen"? --Iantresman 11:16, 4 July 2006 (UTC)

I was perhaps edgy because you twice described phenomena as filaments that are probably shock waves. Besides, not everything has to be filaments; four examples is plenty, particularly if the evidence for filaments is indirect und speculative, as in Hardee. On the other hand, I think Hubble views the Crab Nebula M1 is a rock-solid reference tha some structures in the Crab Nebula are called and are considered to be filaments. I see, no indication that these filaments have anything to do with currents, Birkeland or otherwise, and the wording we choose should reflect that. --Art Carlson 12:17, 4 July 2006 (UTC)

By the way, it sounds like Dickel thinks it's an open question, whether the structures observed in supernova remnants are really (3D) filaments or not. --Art Carlson 12:37, 4 July 2006 (UTC)

I supsect there are views and supporting evidence on both side, and I wouldn't be surprised if both are correct... I don't think they are mutually exclusive. --Iantresman 14:57, 4 July 2006 (UTC)

Plasma parameter

I moved the text and table on the plasma parameter to its own article: trying to avoid getting the reader bogged down in details, but keep the useful writeup. Dashpool 13:21, 8 July 2006 (UTC)

Would it be better to combine the new article with Coulomb collision aka Coulomb logarithm? --Art Carlson 14:00, 8 July 2006 (UTC)

I have no objection to that. However, Coulomb collision as a title sounds very specific: I would have just expected a discussion of the two-body interaction. Dashpool 15:18, 12 July 2006 (UTC)

Peer review

The article has already achieved Good Article status, so I figure that Peer review is the next step for improvement.

Please make comments at Wikipedia:Peer review/Plasma (physics)/archive1 --Iantresman 10:58, 18 August 2006 (UTC)

Plasma shields?

I am an engineering student and I am quite interested in Science Fiction. I have heard mentions of plasma shields in many science fiction films, books and games and I was wondering whether the experts might post something on the article about them. Is there actually a theory behind a plasma 'blast shield' or is it just writers trying to sound cool?

Being science fiction, there is little information on what and how a plasma shield might work. Which isn't to say that scientists haven't thought about a "plasma shield" [19]. But I think this might be better suited to an article of its own, as this is arguably one of the myriad of applications of plasmas. --Iantresman 11:58, 26 September 2006 (UTC)

I think you might be interested in reading the plasma window article. --Art Carlson 12:25, 26 September 2006 (UTC)

I've set-up a redirect from Plasma shield to Plasma window. --Iantresman 12:30, 26 September 2006 (UTC)

i beleive that a plasma shield is simplay a fictional creation created by authors as a piece of fictional equipment. This is because plasma is a higher state of matter thangas, hence it cannot efficiently absorb impacts. It might just combust, or explode. —Preceding unsigned comment added by Polikol22 (talk • contribs) 21:57, 6 November 2010 (UTC)

Experiment

Should something like this be added to the article? An explanation perhaps? http://video.google.com/videoplay?docid=6732382807079775486 --jholdaway 09:42, 18 October 2006 (UTC)

Missing section

This plasma article seems the most appropriate, but a multitude of science fiction has plasma based technologies. Shouldn't there be a "plasma in popular culture" blurb? i kan reed 02:23, 15 November 2006 (UTC)

Plasma modeling

I created a new page on Plasma modeling. I suggest that the mathematical description section in this article be shorter and the details be moved to a new page plasma modeling. --Mindgame123 22:09, 3 December 2006 (UTC)

Popular culture

What's with all those whacko references under "popular culture"? They're obscure, at best. Most are from niche markets, hardly what I'd call mainstream. 129.16.97.227 16:03, 4 July 2007 (UTC)

Fun to make in the microwave?

If no one else noticed, someone should take away "fun to make in the microwave" at the start of the topic. I'm pretty sure it's a pointless joke. I would but I don't have an account. P.S. If I put this in the wrong spot then sorry.

You don't need an account to do this, just follow the instructions. - Saibod 08:12, 21 July 2007 (UTC)

make your own light saber!

if you put one foot on a plasic box and the other on the ground. Put one hand on the ball and the other holding a long plasic rod and turn off da lights. It glows. It's kwl fun for parties. —The preceding unsigned comment was added by OsirisV (talk • contribs) 00:18:25, August 19, 2007 (UTC).

Dark matter edit

I just reverted this edit. I've never seen "phase of matter" refer to anything but baryonic matter. This is clear if you start to talk about the volume fraction of different phases, since dark matter occupies 100% of the volume of the universe, as does dark energy, which should then also be mentioned. The details are explained in the footnote, and I think it's cleaner to leave the whole discussion there. --Art Carlson (talk) 12:07, 20 November 2007 (UTC)

GA Sweeps (Pass)

This article has been reviewed as part of Wikipedia:WikiProject Good articles/Project quality task force. I believe the article currently meets the criteria and should remain listed as a Good article. The article history has been updated to reflect this review. Some areas for improvement follow:

There's some general clean-up that should be done:

• All values should be in the form "number,non-breaking-space,unit" so 20 km would be coded "20 
• All equations should be updated to LaTex style for clarity and consistancy
• A number of new terms where hilighted using boldface—while this does help accessiblilyt to a general reader, "quotes" are prefered for this according to the Manual of Style. I've gone through and changed these where appropriate.

The history section needs the most attention. In highly technical and scientific ariticles, the lead and history sections are most likely to be of general interest, and extreme care should be taken to make them as clear and accessible. See wp:JARGON and [[wp:[edit]Wikipedia:Make technical articles accessible]] for more information.

Re "Common forms" table: Embedded lists with no content are less preferred than prose. Perhaps the commons forms table could be expanded to an "Indented List with content" (see WP:Embedded list for an example)

Definition: In the list of requirements, numbers 2 and 3 should be phrased the same way as number 1. Since all three are requirements, they ought to all start with "something must be something" or similar.

--jwanders^Talk 07:02, 24 February 2008 (UTC)

---

Plasma physics and plasma should be two different articles. If by plasma (physics) it is meant "plasma" itself (which is the way it is understood), we cannot have it at the lower level of "Category:Plasma physics"; it is like putting Category:Astrophysics under either Astronomy article or Physics article.

Sina2 (talk) 17:50, 1 April 2008 (UTC)

Is this intended to mean what it does mean?

"Plasma typically takes the form of neutral gas-like clouds (e.g. stars) or charged ion beams, but may also include dust and grains (called dusty plasmas).[1] They are typically formed by heating and ionizing a gas, stripping electrons away from atoms, thereby enabling the positive and negative charges to move more freely."

What these two sentences tell me is that the "dust and grains" which are sometimes in plasma are "typically formed by heating and ionizing a gas, stripping electrons away from atoms, thereby enabling the positive and negative charges to move more freely".

I believe this to be nonsense and not what was intended. The confusion is caused by several facts.

• grammatically, the word "they" must relate to the noun(s) that immediately precede it ie. "dust and grains", not the word "plasmas" which is the subject of the first sentence.
• "dusty plasmas" occur most frequenntly in conjunction with stars, but the word "stars" is bracketed, and therefore a passing example, not related to "dusty plasmas" (grammatically).
• The inclusion of the ""but may also.....etc" is in the wrong place. It disrupts the meaning.

Comment: To the editors of this article, prioritise the information. Don't include any "but alsos" until you have made a clear statement about the subject.

Suggested rewording "Plasma typically takes the form of neutral gas-like clouds (eg. stars) or charged ion beams (eg. lightning). They are typically formed by heating and ionizing a gas, stripping electrons away from atoms, thereby enabling the positive and negative charges to move more freely."

Having removed the reference to dusty plasma, the two sentences now make sense. That "one more fact" can turn a GA into a shamble, or possibly serious misinformtion. (The problem is, that if you know your subject well enough, the misalignment can pass you by.)

• The fact about "dusty plasma" now needs to be reinserted in the appropriate place. Possibly a following sentence such as: '"Some plasmas (is the plural correct?), particularly stellar plasma (is this correct?), may include suspended particles of solid matter and (not "which") are known as "dusty plasma".

NOTE please check for factual accuracy before inserting. Also- not "dust and grains". "Grains of dust" is acceptable, but "dust and grains" implies a windstorm in a wheat-growing area.

Amandajm (talk) 02:53, 19 April 2008 (UTC)

Too technical?

As a layperson in science, I understand the key elements of the article, and believe the level of technicality is necessary. After all, plasma is a technical topic that doesn't need to be understood for everyday life, much like so-called 'rocket science'. Surely therefore, readers of the article will a) have an interest and a sufficient level of scientific knowledge to deal with the topic, or b) only need to read the initial definition to find out what plasma is - fundamentally, a fourth state of matter. —Preceding unsigned comment added by 194.81.36.61 (talk) 11:56, 26 June 2008 (UTC)

Um... What?

"Waves

Since electrons and ions can move independently of each other, we can have plasmons. Plasmons will then mix with photons to give massive polaritons."

Speaking as an uninformed reader, these sentences look a lot like nonsense. What am I missing? I think they should be reworded to be less ambiguous. - Syclamoth

Speaking as an expert in plasma physics, I wasn't able to identify these sentences as nonsense, but I don't understand them either. I also question whether the phenomenon is important enough that it should be included in a survey article. Art Carlson (talk) 10:03, 22 July 2008 (UTC)

Some Comments

Reading through the page, I have a few comments:

I tried to deal with some of these. (AC. "I have other names. If you're interested.") Art Carlson (talk) 14:58, 7 August 2008 (UTC)

In "common plasmas" :
1. Notable plasma physicist Hannes Alfvén also noted that due to their electric charge, very small grains also behave as ions and form part of plasma (see dusty plasmas). Should one not make a comment here that small grains in and of themselves are not charged, they can be charged by interactions with a plasma.

Changed. - AC

2. why is the aurora a plasma? It may be created by charged particles but the light we see is from neutral oxygen and nitrogen that is being excited, not ionized
3. why is the Io-Jupiter flux tube a plasma? It might contain plasma, but it is just a "physical construct" made up from field lines.

In "Degree of ionization":
can have the characteristics of a plasma (i.e. respond to magnetic fields and be highly electrically conductive) However if we look further up what the characteristics are of a plasma in "definition of a plasma" responding to magnetic fields and being highly conductive are not characteristics.

In "temperatures"
Based on the relative temperatures of the electrons, ions and neutrals, plasmas are classified as "thermal" or "non-thermal". I usually define thermal and non-thermal based on the fact whether the distribution function is Maxwellian or non-Maxwellian. But maybe this differs in different plasma disciplines.

I'm inclined to agree with you. Can we find a reference one way or another? - AC

In "waves":
I also do not understand these 2 sentences. But for plasma waves one could easily make a whole separate page.

Nobody does. (See previous section on this talk page.) I'll remove it. - AC

In "filamentation":
The first sentence is not a sentence, it lacks a verb, probably "are seen" instead of "seen"

Fixed. - AC

In "shocks and double layers":
The first sentence is not a sentence, it lacks a logical ending.

Fixed (or at least improved). - AC

In "Electric fields and currents":
Quasineutrality of a plasma requires that plasma currents close on themselves in electric circuits. I fail to see why quasi-neutrality requires this.

Quasineutrality requires that the current be divergence-free. This does not necessarily mean that current loops in any meaningful sense can be identified. I think this is part of the plasma cosmology mindset. I'm a bit afraid to fiddle with this section because I might accidently delete something meaningful but merely unfamiliar. - AC

Sorry but I still don't get this. Quasi-neutrality means that over a large volume compared to the DeBye sphere, the total charge is zero (where there can be deviations within the volume of the DeBye sphere). Now if there would be a current in this plasma J = -ne * ve * e + ni * vi * e, and it would have a finite divergence Div(J) != 0, which basically means that -grad(ne).ve - ne.div(ve) + grad(ni).vi + ni.div(vi) = alpha. There is no reason to assume that this would violate quasi-neutrality. Assuming e.g. no density gradient, this just means that ni.div(vi) = alpha + ne.div(ve). If quasi neutrality holds, i.e. ni = ne this just means that the electron velocity changes in space differently from the ion velocity, which is no problem whatsoever.

And do you mean mainstream plasma cosmology or do you mean electric universe PC? if the latter, I could not care less what their mindset is. --Tusenfem (talk) 11:37, 13 August 2008 (UTC)

Equation of continuity: ${\frac {\partial \rho }{\partial t}}+\nabla \cdot j=0$

Where there is a divergence of the current, the charge density will change with time, so quasineutrality cannot be satisfied except momentarily. Art Carlson (talk) 08:34, 14 August 2008 (UTC)

Oops, I stand corrected, sometimes it's the basic equations that one forgets.

Is there any such thing as "mainstream plasma cosmology"? I was just pointing out that one of the editors of this article was an advocate of plasma cosmology, and that might explain some of the content. If that is the case here, then it should be refactored to the conventional view. Art Carlson (talk) 08:45, 14 August 2008 (UTC)

Well plasma physics does play a role in normal cosmology, but the point is moot, I was wrong.

In "common artificial plasmas":
If we want to adhere to SI we should change Torr to Pascal.

Go ahead, if you want, but in practice this is an area where working scientists often deviate from SI units. - AC

Okay, just my 2 eurocents of comments. --Tusenfem (talk) 12:09, 7 August 2008 (UTC)

A question

Does somebody have information about the flammability in the plasma (state of matter)?

Thanks,

--190.67.186.169 (talk) 18:53, 13 August 2008 (UTC)

I don't understand your question. You might say a plasma can't burn because it's already hotter than a flame. Art Carlson (talk) 08:33, 14 August 2008 (UTC)

Shape and Volume

The article says: Plasma does not have a definite shape or a definite volume.

What exactly does this mean? Can't I take an enclosed ball of gas of definite volume, energize it into plasma, and call it "plasma of definite shape and volume?" Ungtss (talk) 12:37, 6 December 2008 (UTC)

A solid object has the same shape and volume whether you put it in a bucket or a vase. A liquid will change its shape to fit its vessel, but keeps its volume. A gas - or plasma - will not only take on the shape of its vessel, it will expand to fill it. That's what the sentence means; whether it is a good sentence to have in the article is another question. --Art Carlson (talk) 16:53, 6 December 2008 (UTC)

Awesome -- thanks for the clarification. I'll fix. Ungtss (talk) 17:07, 6 December 2008 (UTC)

Thanks. That's an improvement. --Art Carlson (talk) 19:43, 6 December 2008 (UTC)

State

I thought plasma was a different state of matter. Isn't saying "In physics and chemistry, plasma is a partially ionized gas" like saying "In physics and chemistry, a liquid is a melted solid"? 75.118.170.35 (talk) 17:39, 30 December 2008 (UTC)

State of matter is not a particularly rigorously defined concept. The idea of this sentence is to give a quick orientation about what a plasma is. I'm a plasma physicist, and I usually think of a plasma as just a gas with a large electrical conductivity. That gets you pretty far. --Art Carlson (talk) 18:58, 30 December 2008 (UTC)

Bit isn't describing it as an ionised gas fairly misleading as plasma exhibits some very different behavior? I used to work in plasma physics and most of what I learned was how plasma is different to ionised gas. Adwol (talk) 11:50, 6 January 2010 (UTC)

Plasma a distinct state of matter. The lede says that plasma is a type of gas. But I believe that the definition precludes it from being a gas. Art, yes, it is true that this is just going off a definition, but the definition isn't so undefined, as you say. Plasma has gas- and liquid-like properties. That's why it is a state of matter distinct from a gas. ask123 (talk) 04:55, 7 February 2010 (UTC)

I just spent some time browsing. In Internet a plasma is sometimes defined as an ionized gas, but sometimes it is emphasized that a plasma is not a gas. The few text books on my shelf don't really settle the question either. The definition I like best is from Chen's Introduction to Plasma Physics:

A plasma is a quasineutral gas of charged and neutral particles which exhibits collective behavior

This might serve as a compromise since the equality "plasma = gas" is somewhat weakened. I think Chen is a good source because it is a commonly used textbook aimed at an undergraduate audience (but still often used in graduate studies), which is about the ideal level for a Wikipedia article on this topic. If you look at the article on State of matter, you will see that "state of matter" is also not so easy to define. It is easier to unambiguously identify states of matter when there is a first-order phase transition. There is no such transition going between a gas and a plasma. One thing I don't like about the new edits is the emphasis on "high energy". It is possible under various circumstances to have a cold plasma. According to the Saha ionization equation, this can even be the case in thermal equilibrium if the density is low enough. There are also a number of statements that don't make sense, like "plasma molecules can flow in a coalesced unit". I will revert the edits because I think the old version is definitely clearer and more accurate, but am willing to help find a different definition that makes everybody happy. --Art Carlson (talk) 10:14, 7 February 2010 (UTC)

I think this is just another case of sloppy language in physics, or perhaps just sloppy language in beginning physics text books. I think my following explanation would be clearer than what's been said so far:

In physics, a plasma is a rather tenuous collection of particles that is ionized to some degree, meaning that some portion of the particles is charged and some portion is neutral. The particles may be fundamental particles and/or composites such as atoms or molecules. Is a plasma a gas? A gas is an equally vaguely defined state of matter, and the relationship between these definitions determines whether a plasma is a gas or not. What is clear is that a plasma is a different state of matter than a gas made of neutral particles, a "neutral gas". If one's definition of "gas" is equivalent to "neutral gas", then a plasma is not a gas. (We could come up with a word for "tenuous collection of particles", and both plasmas and gases would fall into that category.) If one's definition of "gas" accepts "ionized gas" as a subset of gases, then a plasma is a gas, since a plasma could then simply be defined as an ionized gas. (An "ionized gas" could also be called a "quasineutral gas".)

Now, it seems to me that if anyone says "a plasma is an ionized gas", they have stated either 1) that a plasma is a special kind of gas, or 2) a poor definition (analogous to the "liquid is a melted solid" example given above), which can easily be mistaken for statement 1. That causes immense frustration when these same people then go on proclaiming that a plasma is not a gas. --Zeroparallax (talk) 07:15, 5 April 2010 (UTC)

We are really just talking about the lead sentence, aren't we? By the time we get to the third sentence we are already starting to work on the distinctions between plasmas and (other) gases and describe it as a distinct state of matter. For those who read farther, there are complete sections on Definition of a plasma and Comparison of plasma and gas phases. The classical way (not always the best way) to resolve disputes in Wikipedia is to cite authoritative sources. I have offered Chen, and would be willing to use and cite his definition in the lead. Do you have a RS contender? There are other ways we could modify the current definition. Perhaps, "plasma is a gas-like state in which a certain portion of the particles are ionized". Nothing I can think of is as crisp as the current version. Would you like to make a suggestion? Just for the first sentence. I find a number of problems with replacing the lead with your paragraph above. --Art Carlson (talk) 10:13, 5 April 2010 (UTC)

The lead sentence (and whatever definition you use for "plasma", and for "gas" and "liquid", for that matter) is very important. As it stands right now, I'd say the whole first paragraph is made contradictory because of the lead sentence (since the lead sentence says "plasma is a gas" and later in the paragraph it says twice that plasma is "unlike gas".) That kind of confusion could dissuade people from even getting to the later sections that help to clarify but do not resolve the contradiction. Does "RS" mean "respected source"? I looked up a definition in one of my most respected sources (the Oxford English Dictionary) and found a definition that is more broad than I expected:

6. Physics. An ionized gas containing free electrons and positive ions, formed usually at very high temperatures (as in stars and in nuclear fusion experiments) or at low pressures (as in the upper atmosphere and in fluorescent lamps); esp. such a gas which is electrically neutral and exhibits certain phenomena due to the collective interaction of charges. Also: an analogous collection of charged particles in which one or both kinds are mobile, as the conduction electrons in a metal or the ions in a salt solution.

1928 I. LANGMUIR in Proc. National Acad. Sci. U.S.A. 14 628 It seemed that these oscillations must be regarded as compressional electric waves somewhat analogous to sound waves. Except near the electrodes..the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is very small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons. 1930 Physical Rev. 37 1467 The plasma used in this investigation was the positive column of a mercury arc. 1958 Engineering 31 Jan. 134/2 The stable plasma reaches the high temperatures, of the order of 5 million deg. K., necessary for producing thermonuclear reactions. 1969 C. STEELE & B. VURAL Wave Interactions in Solid State Plasmas i. 4 In a metal like copper, the free electrons comprising the plasma are electrically compensated by the positively ionized copper atoms. 1971 E. NASSER Fund. Gaseous Ionization & Plasma Electronics xiv. 427 Liquid plasmas exist in salt solutions where the positive and negative ions move separately. 1976 T. BEER Aerospace Environment i. 16 The solar wind is a plasma of hydrogen ions (protons) and electrons travelling at speeds that range from 300 km s-1 to 1000 km s-1, depending on solar activity. 2001 South China Morning Post (Hong Kong) (Nexis) 12 Mar. 1 For up to 10 hours a day, he plays a game called Quake III..blowing holes in terrorists, watching their crimson innards splatter as he reloads his plasma gun.

So if we use this source, in general, we could write "In physics and chemistry, a plasma is a collection of particles or a fluid made of particles where some non-zero fraction of the particles is mobile and some non-zero fraction of particles is charged; the word plasma often refers to an ionized gas that is, on the whole, neutral. The particles may be fundamental particles and/or quasiparticles and/or composites such as atoms or molecules." To illuminate this definition, examples such as those above could be cited. For clarity, a gas made of neutral particles may be called a "neutral gas" and the article can distinguish between "ionized gases" and "neutral gases" rather than the vague or poorly used terms "plasmas" and "gases". --Zeroparallax (talk) 18:15, 5 April 2010 (UTC)

Or we could write, "In physics and chemistry, a plasma is an ionized gas containing free electrons and positive ions". --Art Carlson (talk) 21:08, 5 April 2010 (UTC)

That definition is too vague because "ionized gas" can be taken to mean 1) "a gas made of ionized particles" or 2) "the non-gas state reached after a gas has been ionized". As long as we clarify which phrase is usually meant, then it would be fine, and it's nice because it elaborates on the meaning of "ionized". That is, it would be fine assuming that the usual sense is captured by one of those two options; I'm not a plasma physicist, so I'm not sure. The person above (Adwol) who said "most of what I learned was how plasma is different to ionised gas" might disagree with these options, though! Anyway, this would be a satisfactory definition only if the rest of the article is made to agree with it. That means that if option 1 is selected, we would have to say "plasma" is a "gas" (a particular kind of gas), "plasma" is a different state or phase of matter than a "neutral gas", and almost every instance of the word "gas" in the article would have to be replaced by "neutral gas". If this is disagreeable, then I think it's necessary that the technical definition (after the lead, perhaps) not refer to gas but something else, such as "collection of particles". If both of these options are disagreeable, then I think it's a shame that so many physicists tolerate contradictory terminology, and we should explain the two different perspectives in the article.

Also, somewhere in the article we might want to mention these general(ized) uses of the word "plasma" that refer to mobile-charge fluids. --Zeroparallax (talk) 05:12, 6 April 2010 (UTC)

Ooh, I just found another cool generalized use of the word plasma on wikipedia itself, where not only "particle" is generalized to quasiparticle (a 2D vortex center), but "charge" is generalized to circulation direction (or "multiplicity", since it acts analogously to charge and could be called a charge). This can be found in the article on the Kosterlitz-Thouless transition in the Rigorous Analysis section.Zeroparallax (talk) 19:03, 22 April 2010 (UTC)

My contortions on this article and talk page

I just untangled the histories of plasma (physics), plasma, and their respective talk pages, after a botched history merge. A related talk page archive can be found at Talk:Plasma/Archive 1. Graham87 17:15, 23 January 2010 (UTC)

Viscosity

Someone please add some info about viscosity properties of plasmas! —Preceding unsigned comment added by 91.99.166.80 (talk) 13:58, 26 January 2010 (UTC)

Solar Wind density

Although shown in the Range of plasmas diagram, it isn't clear what the electron density of the solar wind is and this seems like an important figure.

Does anyone have a cited source for this? Makkasu (talk) 17:32, 27 January 2010 (UTC)

"Made of plasma"

Is it correct to say that stars are "made of plasma"? Isn't that like saying rocks are "made of solid"? Wouldn't it be more correct to say "stars are plasma" (or plasmas - I'm not sure what would be the most appropriate pluralization; "rocks are solid" and "rocks are solids" both seem reasonable but probably have subtly different meanings). Wardog (talk) 11:06, 25 February 2010 (UTC)

99.60.127.153 (talk) 23:20, 22 July 2010 (UTC) Made of plasma double layers in space would be what the public has been told is 'galactic lensing?'

Flame

Is usual flame a plasma? I heared that a flame over a candle can be moved by a magnet... —Preceding unsigned comment added by MathFacts (talk • contribs) 2010-04-19T15:28:39

Try Wikipedia:Reference desk/Science, please. - 2/0 (cont.) 16:10, 19 April 2010 (UTC)

I believe flame is intact atoms emitting light and heat. It's not plasma because the nuclei have their electrons intact and so it isn't extremely high temperature plasma. I guess flame is actually a "gas" that is emitting light because it is the visible chemical reaction of heat making chemicals or elements bond or split apart. Where the flame ends is the place where the gasses created cool down enough to stop emitting light photons, Radical Mallard (talk) 19:22, 15 July 2011 (UTC)

State of Matter?

Is plasma officially (or generally) accepted as a state of matter? The first sentence of the article calls plasma "A state of matter which..." A number of different sources (including websites, books, and people) are disagreeing on the topic, and I wondered if there was an official position taken up by any international boards or committees on whether plasma was a constant state of matter which could be achieved by any substance, or whether it was just a freak of nature that only affected certain elements and compounds. Awesome article, by the way. — Preceding unsigned comment added by Edocsil6437 (talk • contribs) 01:03, 16 March 2011 (UTC)

It is a state of matter, yes. solid, liquid, gas and plasma are the forms, I believe. Radical Mallard (talk) 19:22, 15 July 2011 (UTC)

Introduction Quote

"We shall use the name plasma to describe this region containing balanced charges of ions and electrons"

This obviously comes directly from an academic work of some sort, and the wording seems to implyimplies that this is not a standard definition, i.e., the normal definition is more general, and he is reducing ambiguity for the purpose of his work. As a non-expert, I think that it should be noted after the quote whether or not this article adopts the same convention. 74.94.233.237 (talk) 12:04, 5 July 2011 (UTC)

Er, yes, it is a direct quote from the source cited at the end of the quote - http://www.pnas.org/content/14/8/627. In 1928 the given definition of plasma was not the standard one because this state of matter was not called plasma until Langmuir. I have tried to clarify this; please come back or fix it if this does not help. - 2/0 (cont.) 16:21, 5 July 2011 (UTC)

3 Major Types of Plasma

Is it worth pointing out that there are 3 major types of plasma? (1) Electroplasma - free electrons and ions (atomic nuclei). (2) Nuclear Plasma - free electrons and protons (neutrons and neutrinos would escape). (3) Subatomic Particle Plasma - free electrons and quarks. (only existed at the early part of the Big Bang.) Each type has an order of magnitude higher temperatures. -- Radical Mallard (talk) 19:27, 15 July 2011 (UTC)

Introtext is misleading

After sufficient heating a gas dissociates its molecular bonds, rendering it into constituent atoms. However, further heating may also lead to ionization...

This suggests that plasma consists of ionized atoms and electrons. I tried to change that but user Materialscientist corrected that plasma can consist also of ionized molecules and electrons. So what is the fact? Also I think that plasma should be defined more popularily in the introtext. --PlasmaSoul (talk) 09:13, 14 August 2011 (UTC)

I've tried to rewrite that. Correct me at will. Plasma can be atomic or mixed atomic/molecular (or etc.), and the degree of molecular dissociation can be anything between almost 0 and almost 100%. Materialscientist (talk) 09:44, 14 August 2011 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Plasma (physics)/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

We need a 3rd grade edition nice article!!!!!!!!!!!!! — Preceding unsigned comment added by 125.60.227.223 (talk) 08:09, 27 July 2011 (UTC)

Last edited at 08:11, 27 July 2011 (UTC). Substituted at 15:34, 1 May 2016 (UTC)

Flames

Unfortunately I can't edit this page myself. Too bad, but I hope someone will read this and do the correction.

In the "common forms of plasma" we have "Some extremely hot flames [citation needed]".

First of all - the citation can be found in the "flames" article:

Secondly, that citation doesn't claim that only "extremely hot flames" are plasma, but rather that ALL flames are plasma, including the flame of a candle: "What about fire? The flame of a burning candle is ionized, as we now know, and thus a plasma". So the article should be corrected by replacing "Some extremely hot flames" with "The flames of a fire (even candles)". 85.250.65.114 (talk) 10:38, 27 May 2012 (UTC)

I agree that this should be fixed. There's a nice YouTube video called "Electric Flame" (linking to youtube is so complicated). It demonstrates that flames contain ions. Tadmuck (talk) 19:10, 2 March 2013 (UTC)

What about the CRT

Does a cathode ray tube, or for that matter, any vacuum tube have a plasma? I like to saw logs! (talk) 06:17, 30 January 2013 (UTC) according to deffinition, yes. it is ionized gas--205.215.84.77 (talk) 17:28, 30 April 2013 (UTC)

secondary plasma field

when a secondary plasma field is generated by the interactions of certain metals and the primary plasma field ,a wide variety of observable phenomenon,may be viewed.finer metals and meshes work the best as hard or dense metals absorb to much themselves. the particular interaction between steelwool and stainless steel and the secondary field should be done under controlled conditions, as the steel wool will combust. the interaction with carbon to absorb ,ie your radio station signal within a reasonable distance to secondary field 12 feet or more. a third plasma reaction with yet a third gas will definitely bring more interesting observation. Ronald sykes 50.93.20.150 (talk) 05:51, 13 July 2013 (UTC)

plasma field interaction to create motion

With the use of a simple glass plasma globe,filled with various gasses,and the interaction with a non magnetic stainless steel mesh,wrapped over said globe, the interaction with the cosmic fields around us and outside earths vacume can be observed. with the use of common diodes and some newer materials ie. the new dimmer switches ,paired, a dual high voltage generator, a secondary evacuated gas tube,a 1 to 1 induction transformer and various arangements of capacitors,diodes and resistors, to create a varying field . this varying field effect will interact with a magnetic field,causing a varying flux, creating an observable up and down motion, if components are poised properly.although plasma interaction with the stainless steel requires a source of negative ions to perform the said function,this problem can easily be solved either by holding the ground source your self,as the human body is a type of plasma,the use of a ground wire to earth, or another source of non magnetic stainless steel.Ronald sykes (talk) 22:52, 21 July 2013 (UTC)

Nuclear Pasta

There are 5 states of matter now, another Pluto incident. Drrake (talk) 03:49, 24 July 2013 (UTC)

Contradiction?

The article refers to the electrons in a plasma as not actually being "free":

"It is important to note that although they are unbound, these particles are not ‘free’."

But the electrons are later referenced as "free electrons" here:

"The term "plasma density" by itself usually refers to the "electron density", that is, the number of free electrons per unit volume."

Would "unbound" not be a better term? Ducksandwich (talk) 15:17, 4 November 2013 (UTC)

A Conditions of Plasma

→Why debye length should be less than plasma length?(ZK)Plasma group please answere..'— Preceding unsigned comment added by Zikizk (talk • contribs) 10:23, 10 February 2014 (UTC)

Heat transfer

(ZK) Added image description from the potentials section to heat transfer, here. Prokaryotes (talk) 21:09, 5 April 2014 (UTC)

Multipole resonance probe

The wiki needs a new article about the multipole resonance probe, developed by a group of scientists at the Ruhr University in Bochum Germany. It is a new diagnostic approach for plasma measurement.37.201.241.10 (talk) 15:34, 6 November 2014 (UTC)

Meaning of "definition"

In section 1.1 it states:

A definition can have three criteria:

Does this mean that the following three "criteria" must be met for the system to be called plasma? If so, this should be stated directly.

Note also that the three "criteria" are not binary tests (the usual meaning of criterion), but ratios that must come out large in order for it to be considered a plasma (assuming this is the intention). Then being a plasma is a matter of degree, and this should be reflected in the language chosen. 89.217.22.3 (talk) 09:11, 8 November 2014 (UTC)

Plasma parameter

I flagged the phrase "plasma parameter" in two places. It is used in two different senses - in the first case as the particular ratio Λ, in the second as any of several numbers. 89.217.22.3 (talk) 09:11, 8 November 2014 (UTC)

State of matter

I didn't see any citation for plasma being a forth state of matter. I came here looking for evidence of it but all I could find was a table that seems to be trying to show that it is a 4th state but it's not very convincing. Specific question I am left with: If gases become plasmas when they are ionized, why do liquids not have a separate state of matter when they are ionized? Calling plasma a separate state of matter seems premature since they are apparently still being heavily researched and it also seems like something self-important physicists would claim, hence why I am looking for the actual citations.

Also, why is this article restricted to (physics)? shouldn't it also have a (chemistry) entry or preferably none of these parentheses at all? esp. given its status as 4th state of matter it would be of interest to students of chemistry69.223.177.179 (talk) 23:24, 16 January 2012 (UTC)

"State of matter" is not such a well-defined concept that everyone agrees on what is or isn't a separate state, and consequently it isn't of central importance to the physical sciences. There is a disambiguation article on Plasma, without parentheses, but chemists will be interested in the same definition of plasma as physicists. Art Carlson (talk) 07:51, 17 January 2012 (UTC)

It's really considered to be "common knowledge" that plasma is considered to be a fourth state of matter.  ;) — Preceding unsigned comment added by 68.196.248.241 (talk) 01:11, 16 June 2012 (UTC)

And should be considered the "First" state of matter, not the fourth - since even in Big Bang cosmology the first state of matter was plasma. So shouldn't we call it what we really believe it to be? Steven J White (talk) 13:48, 9 November 2014 (UTC)

Removed ball lightning

I have removed ball lightning because the page linked doesn't even say what it is, so we can't say it is plasma. From the page: Ball lightning is an unexplained atmospheric electrical phenomenon. The term refers to reports of luminous, usually spherical objects which vary from pea-sized to several metres in diameter. It is usually associated with thunderstorms, but lasts considerably longer than the split-second flash of a lightning bolt. Many of the early reports say that the ball eventually explodes, sometimes with fatal consequences, leaving behind the odour of sulfur. [23 May 2006] Iæfai (talk) 02:52, 19 March 2012 (UTC)

You should put it back, being as we know it is an atmospheric electrical phenomenon - and only plasma's are highly electrically conductive in gaseous states. Steven J White (talk) 13:53, 9 November 2014 (UTC)

Definition in Introduction

Not to nitpick but since this is a physics-related topic and a certain amount of "rigor" might be expected, I wonder if it might be more appropriate to say that plasma is a *kind* of matter, or *form* of matter; rather than a "state of matter." After all, plasma is an actual "physical substance" with mass, electrical charge, etc., it's not just a state, it's the actual matter itself. "State of matter" implies that Plasma = state - - but Plasma *is* matter. I only mention it since, like I said, it's a physics-related article and a certain amount of "rigor" might be appropriate.

I think "state of matter" is more appropriate, similar to its use when describing solids, liquids and gases. They could also be argued to be "kinds" or "types" of matter, but we are describing the state of matter here. --Iantresman (talk) 22:34, 8 November 2012 (UTC)

Yet in cosmological theory, plasma was the first state of matter to exist - and 99% of the universe "still" exists in this state. Still has not condensed into states of matter that have equal numbers of protons and electrons - solids, liquids and gasses - to which it behaves nothing like. It is the most unique "state" of matter there is, to which nothing else can be compared.. Steven J White (talk) 13:56, 9 November 2014 (UTC)

US or British spelling?

At the top of the article it states --THIS ARTICLE HAS BEEN STARTED IN US SPELLING. PLEASE KEEP PER WP:ENGVAR --

Actually, it wasn't. The first version appears to use British English[20]. The clue is the spelling of "behaviour".

I only raise this because a recent revert [21] seems a bit picky? Aarghdvaark (talk) 03:05, 9 December 2014 (UTC)

Comparison to the gas phase

In the section "Comparison of plasma and gas phases", the text reads that plasma ".. is closely related to the gas phase in that it also has no definite form or volume".

One of the characteristics of plasmas, is that it may indeed have both definite form and volume, eg. filamentation, the stars, heliospheric current sheet, etc. Should we reword, or find a different similarity? --Iantresman (talk) 22:59, 8 November 2012 (UTC)

I agree, which is why I protested when they took out the part about it having a behavior uniquely different from gas. Plasma (highly charged matter) has nothing in common with "neutral matter." We don't even use the same physics to describe each one. Steven J White (talk) 15:08, 20 February 2015 (UTC)

'...Even black holes' (disapprove of this description)

Even black holes, which are not directly visible, are fuelled by accreting ionising matter. This is a weird assertion; that black holes are 'fuelled'. I cannot find any support for that idea in the reference either. 70.185.104.164 (talk) 06:39, 21 April 2013 (UTC) BGriffin

Because they are Z-Pinches in a universe 99% plasma.

Simply charged particles orbiting a common electromagnetic center - not particles orbiting a point object of zero volume. See 2:23 timeline in the following.

https://www.youtube.com/watch?v=kanYuBptuZ0 Steven J White (talk) 15:09, 20 February 2015 (UTC)

Steven, If you think you see a way to improve the article, then please improve it. Isambard Kingdom (talk) 15:24, 20 February 2015 (UTC)

Chemist begs to differ, apart from much clearer, further substantiation

I have read here, and elsewhere at WP, that it is common knowledge that plasmas are a forth state of matter, alongside s-l-g. Like an earlier reader, I reply that the article does not make this clear, from a scholarly perspective—I do not see the substantiation, that there is acceptance, broadly, across the relevant fields—which include chemistry of all stripes—that plasmas should be considered and taught as a fourth state.

Perhaps differences between my and others asking this before me are that I am a chemical professional, active in research, teaching, and writing, and that I see the following, seemingly clear conundrum:

If the heating, EM field, laser, or microwave perturbation required to create a plasma "decreases or increases the number of electrons, creating... ions"... [a process] that "is accompanied by the dissociation of molecular bonds present"^{[ref name="Sturrock"]}… [emphasis added], then this is not a physical change of state at all, but rather a clear chemical reaction whose atomized products present very unique and seemingly (cosmically) very important physical properties. Illustrate it generally how you will, promote it how you will, there is no plasma state of aspirin, and converting aspirin to a CHO plasma is not a physical change of the state of this matter—though the same 2-(acetoxy)benzoic acid does enter the liquid state at 135°C (its m.p.), and can be taken without decomposition into the gas phase using electrospray MS methods. So, at first glance to this chemist, this purported general change of gases to plasmas is not a [general, accessible, real] fourth general physical state of matter. And if I see this, in passing here, I can guarantee that there are colleagues of mine who, on hearing of this "pitch" for the implications of plasma research, have already commented similarly, in print.

Moreover, like other such topical matters at WP that appear repeatedly in articles because it is someone's favorite subject, "plasma as four state" is not verified, broadly, where the claim appears in WP articles, from the required secondary sources—including chemical. It it can be done, so it is clear that all the physical chemists everywhere ascribe to this, then include the array of best citations wherever the claim is made. If it cannot be made so unequivocally among academicians—as I am guessing must be the case—that is, if there is a static preponderance of expert opinion that is not in full agreement to this "four states" paradigm/conceptualization, then it ain't so (current representation does not cut it). If this is the case, the other expert opinions need to be stated here also, even if in the minority of those writing about it. We are not to present something as a done deal, when there are expert "hold outs".

Otherwise, note, citing of self-published academician course notes as sources—this does not help the case for persuasion at all. Reply here as you will, and I will hold breath to hear how I am fundamentally misguided. Cheers. Le Prof [a chemist who has experienced three states, for >50 yrs] Leprof 7272 (talk) 01:13, 3 July 2015 (UTC)

Thank you for writing this. It allows me to think of plasma in a different light. As well, do you have an opinion of supercritical matter? Could that be considered a fifth state? Wavyinfinity (talk) 20:01, 10 July 2015 (UTC)

Recombination?

When a gas is heated or subjected to strong EM radiation it ionizes. That is clear to me. Why is there no mention of plasma recombination, meaning that when it cools it will go back gaseous state and release heat, an exothermic reaction? It is like talk of water being vaporized only to produce water vapor, but condensation... nope. Rain doesn't exist.Wavyinfinity (talk) 20:07, 10 July 2015 (UTC)

Plasmas generally have both ionization and recombination processes happening simultaneously, leading to an overall degree of ionization, as described in the article. Unlike the liquid-air case, there is no first order phase transition between ionized and recombined constituents. --Mark viking (talk) 00:40, 11 July 2015 (UTC)

Disputed - "Plasma is the most abundant form of matter in the Universe, because most stars are in a plasma state."

I was going to add a disputed tag, but I'll just post it in the talk page first and add it if I get no responses here. This statement says it is the most abundant form of matter, but I'm pretty sure that title goes to "dark matter" or "dark energy," which while not characterized well in physics, has for more mass in this universe than regular matter we can see. Since we can only see it's effects on regular matter it may have been discounted. Maybe a qualifier should be added, like excluding dark matter and energy, or "regular matter," unless there is a more suitable term. If you disagree let me know why it should be called the most abundant form of matter.Wgfcrafty (talk) 07:22, 24 June 2014 (UTC)

You're right and wrong(?). I think yes, that plasma is the most abundant, non-dark matter. As I understand, dark matter (and much else in physics, particles/constants etc. cosmological constant) are "invented", to make the data fit the theory. "dark matter" is a huge unexplained gap. It may or may not be needed. I just recently saw that (could look it up), that "dark matter" may after all, be explained by some non-exotic particle after all.. One other, is Modified Newtonian dynamics (MOND) that I think is an older alternative, that fits the motion of galaxies, but may not "explain".. I think it is not saying exotic "dark matter" is needed.

Dark energy (the cosmological constant?) is however not matter and thus doesn't enter into this. comp.arch (talk) 09:48, 21 August 2015 (UTC)

"Science Fiction" section should be removed or rewritten

As is, this is unsourced and ... interestingly non-mainstream ... speculation. 129.67.118.111 (talk) 04:47, 12 January 2016 (UTC)

It's really misspelled too. "String physicist Michio Kaku thinks that plasma saber is the closest practical possibility of awesome weapon cause we can't have star wars light saber. However lots of research and work is required before we can realise that. We would need the power source to be extremely mobile something you can expect to not see for at least 20 years and the materials that can withstand extreme temperatures .These materials(ceramic fibres) exist but major modifications and improvements are needed. The plasma would be controlled by electromagnetic waves. A simple solution is to wound coils around it and pass current so that it is contained by magnetic field." It looks like a child wrote this thing. Somebody get it outta here. 108.208.70.47 (talk) 22:17, 12 January 2016 (UTC)

Semi-protected edit request on 16 January 2016

The "Science fiction" section should be removed - it's poorly-written, unsourced speculation.

99.236.5.200 (talk) 18:27, 16 January 2016 (UTC)  Done Isambard Kingdom (talk) 19:01, 16 January 2016 (UTC)

Requested move 10 March 2016

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: Not moved. (non-admin closure)  — Amakuru (talk) 11:11, 18 March 2016 (UTC)

---

Plasma (physics) → Plasma – All the other things we call "plasma" are already specified in the title (i.e. Blood plasma). While we also have the subject in parentheses for Plasma (mineral), it is only a redirect. We should really have this take precedence, since it is one of the most known articles and is the only thing simply called "plasma". AYFKM (talk) 18:20, 10 March 2016 (UTC)

• Oppose this needs to stay a dab page. In ictu oculi (talk) 20:53, 10 March 2016 (UTC)

Why? Energy doesn't need to be a disambiguation page, it just goes straight to the physics definition. AYFKM (talk) 21:12, 10 March 2016 (UTC)

• Support - Clear WP:PRIMARYTOPIC. Oppose - IP below makes a persuasive point. (Note that if accepted Plasma → Plasma (disambiguation) would also need to be performed.)  InsertCleverPhraseHere  04:54, 11 March 2016 (UTC)
• Strong oppose just because the topics reside at different titles does not make this the primary topic by default. All other uses still need to be considered to determine primarity, and I see no reason to delete the disambiguation page either, for the same reason, that "plasma" refers to all the uses listed. Indeed, a primary topic argument can be made that "blood plasma" is the primary topic for "plasma" since it is very commonly called "plasma" and appears very frequently as such in the world at large -- 70.51.46.39 (talk) 05:46, 11 March 2016 (UTC)
• Oppose For the same reason stated by the IP editor above (70.51.46.39) --Guy vandegrift (talk) 06:55, 11 March 2016 (UTC)
• OP, you imply that only parenthetically disambiguated terms need be considered when determining if there is a primary topic. Can you explain your reasoning a little more? It seems to me that blood plasma and plasma (physics) are both roughly equally likely to be the intended target of a search for "plasma", so there is no WP:PRIMARYUSAGE. VQuakr (talk) 08:02, 11 March 2016 (UTC)
• Oppose. No evidence that the physics term is more common than the medical term. Axl ¤ [Talk] 13:05, 11 March 2016 (UTC)
• Oppose. For same reason, no evidence that the physics term is more common than the medical term. Also, this sort of suggestion often ends up being a distraction from more pressing issues of content. Isambard Kingdom (talk) 14:11, 11 March 2016 (UTC)
• oppose as Louie496 points out (below) neither should be treated as primary--Ozzie10aaaa (talk) 15:01, 11 March 2016 (UTC)
• Information Plasma (physics) shows 3687 page views per day, Blood plasma shows 2216. So although the physics article does draw more views, the balance is close enough that neither should be treated as primary. Looie496 (talk) 14:37, 11 March 2016 (UTC)

The guideline says "A topic is primary for a term, with respect to usage, if it is highly likely—much more likely than any other topic, and more likely than all the other topics combined—to be the topic sought when a reader searches for that term" (emph added). So this article gets even less primary when all the pageviews of the other usages in the disambiguation page are considered. VQuakr (talk) 20:29, 11 March 2016 (UTC)

---

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Scope of "space plasmas"

Please see Talk:Astrophysical plasma#Scope of "space plasmas". Thanks. fgnievinski (talk) 16:04, 24 April 2016 (UTC)

Jupiter clarification

"The planet Jupiter accounts for most of the non-plasma within the orbit of Pluto (about 0.1% by mass, or 10−15% by volume)."

0.1% certainly isn't "most". Is this trying to say something about local density? Or should it talk about the percentage excluding the Sun? Or the percentage of mass excluding plasma, and note that the Sun is plasma?

JimJJewett (talk) 16:59, 23 September 2016 (UTC)

Potentially incorrect statement in 2nd paragraph - need a physicist to confirm

Hi this post is about the second sentence of the second paragraph in the article which states:

"This decreases or increases the number of electrons, creating positive or negative charged particles called ions,[2] and is accompanied by the dissociation of molecular bonds, if present.[3]"

Unless my understanding of physics is horribly wrong, electrons are neither created nor destroyed when a gas is ionized. Rather the electrons are stripped away from one species and held by another. The total number of electrons in a given sample would be conserved through the ionization process to create a plasma from a gas. I'm aware that interactions between lone electrons and lone protons could change the total number of electrons present but from what I understand that's not the driving mechanism behind ionization and the effect of those interactions would be relatively small.

Can a physicist weigh in here and confirm or refute my point? Thanks and have a nice day everyone!

129.138.37.190 (talk) 05:38, 28 October 2016 (UTC)

I am no physicist, but maybe a "free" or "unbound" is simply missing before "electrons"? I.e. the number of free electrons changes, and not the number of electrons. Jhertel (talk) 07:45, 31 October 2016 (UTC)

I now changed "This decreases or increases the number of electrons" to "This decreases or increases the number of electrons in the atoms or molecules". I think that brings more sense into it and clears up the ambiguity. It can still be phrased better, though. Jhertel (talk) 08:16, 31 October 2016 (UTC)

Good Article Reassessment

It has come to my attention, after I've translated this article to Chinese, that it really no longer satisfies the GA criteria. My main concern is in the lack of inline citations, or just sources in general. Unsourced are the sections Ranges of parameters, Temperatures, Complete vs. incomplete ionization, Plasma potential, Comparison of plasma and gas phases, Common forms of plasma, Shocks or double layers, Electric fields and circuits, Critical ionization velocity, and Mathematical descriptions. The section Research was also just pulled from some non-authoritative website. There are too many dead links. I'm even slightly embarrassed to nominate it for DYK on the Chinese site. Whereas the general prose of the content seems fine, the article, which was mostly written and made GA in 2006, no longer meets the other criteria Wikipedia has come to develop. I've added the GAR request tag and look forward to the result. Yinweichen (talk) 22:50, 26 January 2017 (UTC)

Agreed. This article is a mess, which continues to tack on mostly irrelevant or of marginal importance subject material. Not all verifiable material is necessarily relevant to this article. You are justified to removed non-conforming material here. Arianewiki1 (talk) 03:24, 28 January 2017 (UTC)

Not only that, but most importantly, much of the article is unsourced.Yinweichen (talk) 16:57, 1 February 2017 (UTC)

@Yinweichen and Arianewiki1: Plasma (physics) has been nominated for community good article reassessment (link -KAP03(^{Talk • Contributions • Email}) 01:25, 22 May 2017 (UTC)

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WP:OWN violation

For whatever reason Arianewiki1 is choosing to violate WP:OWN. For the record "non-consensus edit" is not a wikipedia policy. In fact there is a policy that specifically forbids that: WP:BOLD. It is inappropriate to revert edits without a specific reason, and the fact that an editor has not asked for permission is not a valid reason.

If there is a specific concern, please state it. Otherwise please find some constructive way to contribute to Wikipedia.

-- MC 141.131.2.3 (talk) 00:49, 29 September 2017 (UTC)

The whole process of edit Wikipedia basically boils down to this, someone (you) makes a bold edit, others will review the edit and possibly revert it for whatever reason, you then discuss the edit. In this case, @Arianewiki1: seems to be just as justified in making the revert as you did for initially making the edits. I see no ownership issues here. Sakura Cartelet ^Talk 01:18, 29 September 2017 (UTC)

Disagreement isn't the same as ownership. Focus on the content, not the editor, here on the article talk page. And yes, WP:ONUS is policy. VQuakr (talk) 01:20, 29 September 2017 (UTC)

What nonsense. Boldness is one thing, but it has to be correct and make sense. Also "has not asked for permission is not a valid reason." I have said no such thing. Consensus is not asking permission in any sense.

• This is the edit here. [22] You wrote: "Plasma is a state of matter in which an ionized gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter."

That does not simply define plasma at all, and is so over the top, it utterly confuses any reader. (Even the given cite is 1974.) Frankly, the better definition is that plasma are atoms with significant number of electrons removed. A dictionary definition is like: "An ionized gas consisting of positive ions and free electrons in proportions resulting in more or less no overall electric charge, typically at low pressures (as in the upper atmosphere and in fluorescent lamps) or at very high temperatures (as in stars and nuclear fusion reactors)."

• You also removed the text + cite "from Ancient Greek πλάσμα, meaning "moldable substance" πλάσμα Henry George Liddell, Robert Scott, A Greek–English Lexicon, on Perseus or "jelly") " Complaining "Statement a tad confusing (and maybe misleading)" Say who? Where is the consensus for this?

• You wrote this "...Earth's surface under normal surface conditions..." Is this not alliteration? (I also again removed "(other than lightning)" because it was not true, which is explained here.[23]

• Your complaint "Lead sentence should provide an actual definition of the topic." Yes, but it should be comprehensible too.

Get consensus, and explain yourself, which is what this article's Talkpage is for. Thanks. Arianewiki1 Arianewiki1 (talk) 01:28, 29 September 2017 (UTC)

@141.131.2.3: You wrote here[24] "For the record "non-consensus edit" is not a wikipedia policy. In fact there is a policy that specifically forbids that: WP:BOLD. It is inappropriate to revert edits without a specific reason, and the fact that an editor has not asked for permission is not a valid reason. ...If there is a specific concern, please state it. Otherwise please find some constructive way to contribute to Wikipedia."

Actually WP:CON says: "When editors do not reach agreement by editing, discussion on the associated talk pages continues the process toward consensus." and "When there is no wide agreement, consensus-building involves adapting the proposal to bring in dissenters without losing those who accepted the initial proposal." I wrote in the reason for the revert. "Please use talkpage for further edits."[25] That is Wikipedia policy.

It also says WP:BOLD "Don't be upset if your bold edits get reverted." It also says: "On controversial articles, the safest course is to be cautious and find consensus before making changes, but there are situations when bold edits can safely be made to contentious articles. Always use your very best editorial judgment in these cases and be sure to read the talk page."

As for "It is inappropriate to revert edits without a specific reason..." Says who? I've explained it.

"...and the fact that an editor has not asked for permission is not a valid reason.". Show where I have said this please. 'Consensus' does not mean 'permission'.

"If there is a specific concern, please state it." I now have.

"Otherwise please find some constructive way to contribute to Wikipedia." Considering your claiming WP:OWN and that I historically spent some time stablising this page, then this statement is somewhat contradictory. (Is what I think you are implying is that you just want me to get out of your way.) Really WP:PA does not help get consensus.

Note: Please consider becoming a registered User, as it helps in communication between editors here. (See Wikipedia:Tutorial/Registration) Arianewiki1 (talk) 02:14, 29 September 2017 (UTC)

@141.131.2.3: Any response here??? Arianewiki1 (talk) 00:30, 30 September 2017 (UTC)

State of matter v. Plasma (physics)

I have fixed the article on the State of matter to be in line with Plasma (physics) article, by removing all the contridictions and ambiguities. I will now link State of matter in this article. Any possible Introductory summary should Arianewiki1 (talk) 03:11, 1 October 2017 (UTC)

Working on the lede.

Somewhat independent of the discussion going on above, I do find the first paragraph of the lede inadequate for defining the subject of this article. In reading the first paragraph, the reader is left wonder what plasma is. "Jelly"?, well, obviously not. Perhaps we can use something like "Plasma is a special kind of ionized gas and in general consists of positively charged ions, electrons, and neutrals." -- Taken largely from this intro article: [26] (not my definition). Note that some of this appears in the second paragraph, so we might rearrange material from there. Thoughts? Attic Salt (talk) 03:39, 29 September 2017 (UTC)

"Plasma is a special kind of ionized gas and in general consists of positively charged ions, electrons, and neutrals." A definition of plasma is difficult issue and not simple, because as a form of matter its behaviour is different than an ionised gas. In fact, the difference is by the amount of ionisation, which varies depending on the environment. In this case the electrons are separate from the highly positive atoms, acting like suspension aka jelly . (neutrals are what... Neutrons? Arianewiki1 (talk) 08:37, 29 September 2017 (UTC)

Are you saying you agree or disagree with article I linked above? The article defined neutrals as "atoms, molecules, radicals". Do you agree that the first paragraph needs work? Attic Salt (talk) 12:33, 29 September 2017 (UTC)

The article Introduction is perfectly AOK. Thanks. Arianewiki1 (talk) 00:28, 30 September 2017 (UTC)

Assuming that the first paragraph should provide some definition of "plasma", I suggest that some of the defining sentences in the second paragraph be moved up to the first paragraph. Attic Salt (talk) 03:22, 30 September 2017 (UTC)

Strongly Oppose. Look. I made the change on the 2nd Feb 2017 that added the definition of plasma which is here.[27] Introduction of the first sentence was changed on 24th February, which added a reference to the origin of the name plasma here.[28] The logic of the text is as follows:

• Paragraph 1 : This explains the name origin, then expresses it is the fourth state of matter, and it differs from the other three, because it does not naturally exist on Earth and can only be artificially generated. (All properly cited.)
• Paragraph 2 : Expands the concept by explaining sources and examples of either partial ionised plasmas and fully ionised plasmas: Then says plasma production produces electriv field then magnetic fields.
• Paragraph 3 : Differenciates between chemical ions and plasma

It is written to build up the nature of plasma in a logical order for a complex subject and summarises the order in which it appears in the main text of the article's page. I changed it becauqse the main text is very technical and complex. If you moved the second paragraph to the first one or second sentance, but you can't get past "...although the true technical transition between the two is mostly a matter of nomenclature and subject to interpretation." Putting that in the lead paragraph would confuse things, so ot is better to develop the concept about forms of plasma is a way that is simple to complex.

By saying "I suggest that some of the defining sentences in the second paragraph be moved up to the first paragraph." I would simply disagree entirely, only because it adds no information that plasma is principally the 4th state of matter and differs from the others by needing to be generated and does not exist as the ground state on Earth.

All these changes ave been scutinised for at least six months, and from the history of edits, we can assume some general consensus. I wrote much of this text to stabalise the article to remove past contentions by editors and those who have aimed to cause disruption with an obvious agenda. IMO, either give a better reason to change it, and not react so heavily to cause unnecessary future edits. Thanks. Arianewiki1 (talk) 06:31, 30 September 2017 (UTC)

@Attic Salt: @VQuakr: @Nerd1a4i: I've just made an objective compromise with the introduction to belay these concerns without damaging the guist of the original. I think to newer version is an improvement and is more logical, and retains WP:GF. Please state further issues. Thanks. Arianewiki1 (talk) 04:01, 1 October 2017 (UTC)

"Does not freely exist" mention in the lede

I don't know that this is very clear. Lightning is discussed as an example of producing plasma. And, while it is not "on" the Earth per se, plasma exists in the Earth's magnetosphere. Attic Salt (talk) 13:53, 1 October 2017 (UTC)

@Attic Salt: Give a darn inch and you take a mile. So much for compromise... You just avoiding any consultation at all.

Therefore, I have immediately reverted your edits here because they were nonconstructive edits, and now the implication of the your text was completely wrong. Specifically; "[Plasma]...can simply be considered as a gaseous mixture of negatively charged electrons and highly charged positive ions,..." That does not meet the true definition criteria, because plasma is not 'simple', which is qualified later by saying "Plasma and ionised gases have unique properties and display behaviors unlike those of the other states, although the true technical transition between them is mostly a matter of nomenclature and subject to interpretation." (Here "simple" refers to concept to aid the reader's understanding.)

As I said before (above): "Considering the complexity of the nature and context of defining plasma - especially differences between partial plamsa and fully ionisd plasma - its pure definition will always be contentious."

Again, the Introduction should develop the concept.

1)"Plasma is the 4th state of matter" says and defines what plasma is - a kind of substance. (This has been debated almost endlesslly on this very Talkpage (see Archive 1 discussions), just to reach this consensus.)

2) The reader can then link the properties of plasma as gaseous, which has the additional parameter of influencing fields.

3) Plasma does not exist on the Earth because it needs to be generated. I.e. It returns to the ground state of a gas if the generation is removed.

Hence, the wording here is also implict correct, as it says plasma does not freely exist but must be generated, where the other states of matter DO exist freely. (Clearly, the Earth's magntosphere isn't here on the Earth's surface.) To avoid this confusion, I've restored the wording "under normal surface conditions"

The text "Unlike, the other three states of solid, liquid, and gas, plasma does not freely exist on the Earth under normal surface conditions, and can only be artificially generated by heating neutral gases or by subjecting that gas to a strong electromagnetic field" is now implicitly correct, supported properly + formally cited.

I also removed the incorrect absolute of "is" back to "can be". Arianewiki1 (talk) 23:06, 1 October 2017 (UTC)

Reorganised text.

@Power~enwiki:@Attic Salt:@141.131.2.3: The last changes are reasonable, but make the lede too complex for the average reader. I have restored this back to the original version, and added the additional text back to Definition (with Attic Salt's) which is a compromise reasonable. Accusing me of WP:OWN has been explained earlier in the text, which the IP seemingly has just been ignored. Suggest modifying the Definition section further, before changes in the Introduction. Also suggest this is again presented in talk page, where the Rfc suggest there is nothing wrong with the current introduction. Thanks. 22:23, 9 October 2017 (UTC)

The RFC suggests there is nothing wrong with the introduction? Attic Salt (talk) 22:26, 9 October 2017 (UTC):

First of all User:Attic Salt, let's slow down with these rapid edits. The text has been in this way for a while, and whilst it is important to allow change and evolution in articles, more change with continuous edits just make it more difficult to get it right. [[User:141.131.2.3|141.131.2.3] was provocative and unhelpful, and avoided gaining consensus. (They should have responded to the Section where they falsely accused me of WP:OWN.)

As for "The RFC suggests there is nothing wrong with the introduction?", but really the reverse is also true. (Had you not closed the Rfc when you did, when the admin was finding consensus, you might have solved this.) Where is the WP:Consensus here for the change? Arianewiki1 (talk) 22:43, 9 October 2017 (UTC)

Excuse me? You tried to close the RFC before I did. But, again, where does the RFC suggest "there is nothing wrong with the current introduction"? Attic Salt (talk) 22:47, 9 October 2017 (UTC)

@Attic Salt: Please stop this 'mudding of the waters' by hinging on every word or action I say.

Plainly, near the end of the RFC it clearly says: I.e. "Other editors made comments suggesting that they sympathize with the lede having a defining sentence, though it might be technically difficult to attain an ideal definition: Nerd1a4i, VQuakr, Tigraan.

Only two editors were against the lede having a defining sentence: Arianewiki1 (who "strongly" opposed the suggestion, but he/she might have slightly moved on this), Cwmhiraeth (who felt that a version of the lede (not sure which version) already had sufficient information)."

My count: is 3 for, 3 undecided, 2 against. No consensus. Arianewiki1 (talk) 00:30, 10 October 2017 (UTC)

Sentence change

The article says:

"Unlike the other three states of solid, liquid, and gas, plasma does not freely exist on the Earth under normal surface conditions, and can only be artificially generated by heating neutral gases or by subjecting that gas to a strong electromagnetic field."

It would be better to simplify, (and remove future contentious edits) by saying:

"Unlike the other three states of solid, liquid, and gas, plasma can only be artificially generated (or ionised) by heating neutral gases or by subjecting that gas to a strong electromagnetic field. If the ionising source is removed, created plasma reverts back into a gas."

Any issues in changing this? Arianewiki1 (talk) 04:22, 10 October 2017 (UTC)

I don't see how that's a simplification. It is longer and adds more qualifiers. VQuakr (talk) 06:05, 10 October 2017 (UTC)

New lede proposal

Diff at [29]. I hope this addresses all of the major concerns raised by participants in the earlier RfC. Please feel free to make suggestions either here, or BOLD-ly on the lede itself. If you feel a need to revert to an earlier version, please discuss that here as well. power~enwiki (π, ν) 15:06, 10 October 2017 (UTC)

• Looks good to me. Tigraan^{Click here to contact me} 15:18, 10 October 2017 (UTC)

  Also - I thought it very very hard when writing the above, but I probably have not developed telepathy yet - thank you a bunch for solving the RfC and its fallout. Tigraan^{Click here to contact me} 15:37, 10 October 2017 (UTC)

Thank you. The proposed change to the lede incorporates what the sources (Chen and Freidberg) state is a fundamental defining property of plasma, namely that it exhibits "collective behaviour", which, I note, IS discussed in the body of the article, though perhaps not as much as it should be. As I understand it, it is this collective behaviour that is the reason for the "jelly" analogy in the etymology of "plasma" (but I'm happy to be corrected on this). I also support moving the etymology material to the history section, where some of that content might generate confusion if introduced as the first bit of info in the lede. Attic Salt (talk) 15:21, 10 October 2017 (UTC)

Formal explanation

@Power~enwiki: power~enwiki last edit [30] has made a change without consensus and worst has avoided why we had the Rfc in the first place. All you've done is change this to satisfy Attic Salt and ignored the whole reason for the consensus debate.

Saying "Plasma...is a state of matter in which an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter." when it is not entirely true and at best is misleading It is not just the field production defining a plasma. (Also the statements above by Attic Salt is also not absolutely true, and I believe shows some obvious general misunderstandings.)

Plasma's definition involves several parameters (not one), and much of the confusion is that several aspects of this are universally agreed upon. e.g. When does a gas actually become a plasma? This is why the cited text says: "...although the true technical transition between them is mostly a matter of nomenclature and subject to interpretation."

• 1) A substance becomes plasma for several reason, primarily because of the stripping of electrons by heat or a electromagnetic field, this induces the 'state of matter', which is ionised. It is the freedom of the unbound electrons that generate the fields, so plasma is physically actually the atomic nuclei. e.g. In the Sun's corona is Fe XX (Iron with 19 electrons removed.) That is the 'substance.' This is why the now deleted statement clearly says: "Plasma can simply be considered as a gaseous mixture of negatively charged electrons and highly charged positive ions... True.

The Introduction now doesn't say this.

• 2) The second part of the text qualifies the different behaviours of the freed electrons and plasma ions. e.g. "...however, true plasma production is from the distinct separation of these ions and electrons that produces an electric field, which in turn, produces electric currents and magnetic fields." This is what generates the fields. What happens is the freed electrons are no longer attached to the atomic nuclei, as the energy (by heat) strip them away. The more heat, the more ionisation (stripping). e.g. Fe XX can become Fe XXI, etc. The degree of ionisation determines the difference between partial or fully ionised plasma. (Which is qualified in the next paragraph.) Additionally, plasma is a gas, whose so-called plasma density or electron density determines its behaviour.

• 3) Furthermore, the atomic nuclei become separated and fixed in their place, in the sea of freed electrons, which is why the word 'jelly' is used, as selected by Langmuir in the 1920s. This is why: "...true plasma production is from the distinct separation of these ions and electrons..." True.

• 4) The behaviour of the freed electrons from each nuclei create an electric field, which when combined with many many electron moving freely, makes the magnetic field, which then creates the electromagnetic field. This is the so-called 'plasma state', simply distinguishing plasma from some gas. This is why: "...distinct separation of these ions and electrons that produces an electric field, which in turn, produces electric currents and magnetic fields." True

Now, according to power~enwiki statement: "BOLD - new lede. ...Use a better-written definition." clearly is oversimplified, and the deletion of "Plasma can simply be considered as a gaseous mixture of negatively charged electrons and highly charged positive ions, however, true plasma production is from the distinct separation of these ions and electrons that produces an electric field, which in turn, produces electric currents and magnetic fields." is unjustified. This shows this concisely describes plasma, which elaborates a definition, and is logically improves in complexity, so the average reader can understand what plasma is. The current organised texts read like a university textbook, which assumes already known knowledge.

So far, throughout the lede debate, no-one has truly stated why these present changes are even justified. Worst, there is still no consensus since the changes introduced [31]. The understanding of this topic is complex and broad in scope, so the Introduction has to be viewed as a process and not some 'demanded' one sentence definition.

Until someone can provide a better and broader definition of 'plasma' and can consensus, the explained text above (deleted) should stay in the Introduction.

Note 1: While I've written this text, User:Nerd1a4i has restored this original text.[32]

Note 2: Apologies for the shouting, but I wanted to be implicit with my reasoning. Thanks. Arianewiki1 (talk) 02:15, 11 October 2017 (UTC)

The present version "Plasma is a state of matter which can be loosely defined as an ionized gas, though partially ionized plasmas also exist. This ionization makes the plasma affected by electromagnetic fields, which heavily influence how the plasma behaves." is incorrect. Plasma is a degree of ionisation and not partial or fully ionised, whose accepted definition differs between sources. Also plasma also generates the magnetic field, where the ionisation make these electric field, then the electric current, then the magnetic field. It is a three way process not two.

The article was written in British English not America English where it is 'ionised' not 'ionized.' User:Nerd1a4i changed this. I have now reverted these changes. Arianewiki1 (talk) 02:52, 11 October 2017 (UTC)

@Arianewiki1: I took the sentence "Plasma is a state of matter in which an ionized gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter." verbatim from its appearance in the "Definition" section. In general, the first sentence should say what plasma is, and should avoid content that merely says what it is not, or what it is one of four of. power~enwiki (π, ν) 03:00, 11 October 2017 (UTC)

@Power~enwiki: Ah. Not your fault, as it would be impossible to find in all the edits. I was the one who placed that text down from the lede to Definition as a compromise to solve the dispute here.[33], which I added under section Talk:Plasma_(physics)#Reorganised text. (I pinged you about it to be transparent.) Attic Salt then quickly changes, by duplicated it, then moved it again here.[34]

My explanation and reasoning then appears under section Talk:Plasma_(physics)#"Does not freely exist" mention in the lede

I'm getting really frustrated having to put 'fires out' everywhere, and not have a stable version to work towards consensus. Since the intervention of 141.131.2.3 here [35] more than two weeks ago accusing me of WP:OWN and their initial series of non-consensus edits [36]. Heck, I explained myself to them here.Talk:Plasma_(physics)#WP:OWN violation (I said following accepted Wikipedia policy "Get consensus, and explain yourself, which is what this article's Talkpage is for." The IP didn't respond. Had the normal procedure of using the Talkpage first, we would not be where we are now is such a mess.)

Please. We need a stable version of text to gain and work towards consensus. At the moment, it is like working on a ship in a stormy ocean. I keep trying to drag the pieces together, and are faced with conflicts based on ancillary technicalities and procedures. Yes, I rewrote much of the Introductory text in question and did not make these changes on whim. I've taught on the subject, I'm scientifically trained and understand what I'm doing. Arianewiki1 (talk) 04:16, 11 October 2017 (UTC)

OK. Tigraan appears to have started an RfC that will work better. I haven't studied physics in over a decade, "generally hotter than a gas with different electromagnetic properties" is all that I'm willing to definitively say based on my own knowledge. I don't plan to edit the article further until I'm actually at a library, which won't be for a few weeks at a minimum. power~enwiki (π, ν) 14:17, 11 October 2017 (UTC)

Request for comment

The following discussion is an archived record of a request for comment. Please do not modify it. No further edits should be made to this discussion. A summary of the conclusions reached follows.

Withdrawn. Attic Salt (talk) 08:31, 12 October 2017 (UTC)

---

Should the first paragraph of the lede contain a definition of "plasma"? Attic Salt (talk) 13:38, 30 September 2017 (UTC)

• Strongly oppose It seems that Attic Salt is trying to enforce change regardless of examining the explained reason, and worringly is almost refusing to engage and avoid with consensus the author with the issue. The whole Introduction is supposed to follow the main bulk of the text and summaries its content. (It is not as if there is no definition at all, and is certainly improved from the earlier version.)

My own explaination of why the version should stay have been expressed in the two other sections above.

Considering the complexity of the nature and context of defining plasma - especially differences between partial plamsa and fully ionisd plasma - its pure definition will always be contentious.

Note: Something doesn't quite gel here in the Attic Salt behaviour and that of 141.131.2.3 Sockpupperty?

Attic Salt Are you also 141.131.2.3? Arianewiki1 (talk) 23:13, 30 September 2017 (UTC)

• Comment: Can I just point out that generally the lead is supposed to introduce the reader to the topic? How to define a plasma is indeed complex, but we don't need to give the 100% pure definition here - what if you just said "a plasma can be loosely defined as an ionized gas, though partially ionized plasmas also exist" and go more in-depth into the issue later? --Nerd1a4i (talk) 00:24, 1 October 2017 (UTC)

• Definable topics get defined in the first sentence per WP:LEADSENTENCE. You are unlikely to make much progress, though, on consensus regarding how to best define this topic using that RfC query. VQuakr (talk) 01:00, 1 October 2017 (UTC)

• Yes it should, according to WP:LEADSENTENCE. And I strongly agree with Nerd1a4i that it need not be a 100% self-contained, definitive and accurate definition. In fact, trying to make it so is likely to be counterproductive. William Avery (talk) 17:39, 1 October 2017 (UTC)

• No - The lead section is an introduction to the article and should summarize the information in the body of the text as per WP:LEAD. I think there is sufficient information on the definition of "plasma" currently in the lead to serve this purpose. However the lead currently contains 12 citations, none of which should be necessary in the lead because all the information there should be cited elsewhere in the main body of the article. Cwmhiraeth (talk) 09:47, 3 October 2017 (UTC)

• (bot-summoned) Procedural oppose, moral support I cannot find the relevant policy link right now, but such an RfC should contain a proposed wording, lest there be a thousand follow-up RfC with a proposed wording that fails each time.

This being said, I do think we should put the simplest possible non-misleading definition in the lead. The current wording is Plasma can simply be considered as a gaseous mixture of negatively charged electrons and highly charged positive ions, however, true plasma production is from the distinct separation of these ions and electrons that produces an electric field, which in turn, produces electric currents and magnetic fields, which desperately lacks simplicity (especially behind "however"). I would support Nerd1a4i's wording a plasma can be loosely defined as an ionized gas, though partially ionized plasmas also exist. Tigraan^{Click here to contact me} 09:28, 6 October 2017 (UTC)

"I cannot find the relevant policy link right now," means exactly what? To say "...a plasma can be loosely defined as an ionized gas, though partially ionized plasmas also exist.", means nothing, and worst, then why call it a plasma? - which by definition isn't an ionised gas! Sorry the caeless wording here means zippty dooo dah, and you'll need to be more explicit to advancey the case. (Sadly, Attic Salt knows this, leaving this mess behind. That's why this particular argument is weak.)! Arianewiki1 (talk) 12:44, 6 October 2017 (UTC)

On the policy thing: I would have sworn there is a rule about RfCs that say you should ask a clear choice between multiple stated alternatives, i.e. "should we put <sentenceX> in the article" is OK but "should we talk about X" is not. But I cannot find it right now. False memory maybe...?

On the content: I don't care much about "careless wording" in the lead. We should have something that is not outright false, but anything understandable will do. We can argue the exact wording, but "plasma is ionized gas" or a variant looks like a good starting point to me.

The point is to give something that the average reader of the article (or maybe, the within-two-standard-deviations reader) can understand. I would think most of the English-speaking world has heard the word plasma, if only from movies, so the average reader is statistically more scientifically-illiterate that the average reader of (for instance) Bloch sphere. As an example of how it is done elsewhere: the lead of natural number says the natural numbers are those used for counting, hardly a precise definition, and does not include a reference to the Peano axioms (which are lower in the article body). Tigraan^{Click here to contact me} 13:05, 6 October 2017 (UTC)

Complainent has just retired. Likely just done to cause trouble. Arianewiki1 (talk) 12:58, 6 October 2017 (UTC)

@Arianewiki1: You do not get to close an RfC early just because the initiator has left, especially when you are involved in that RfC. I unstriked all the above. Tigraan^{Click here to contact me} 13:07, 6 October 2017 (UTC)

• Sooo... what is the nature of the matter that is to be commented on? Please see WP:RFC#Statement should be neutral and brief, since most of the above is struck through. --Redrose64 🌹 (talk) 19:43, 6 October 2017 (UTC)

@Redrose64: yeah, another editor had just struck the RfC query and everyone's replies, [37]. I just restored the unredacted version. VQuakr (talk) 22:31, 6 October 2017 (UTC)

@Redrose64:@VQuakr: I have reponded to this here[38], and my reasoning is as follows:

I removed this Rfc towards the Talk:Plasma (physics), as by announcing that Attic Salt had retired clearly implied they were no longer interested in reaching consensus here. I have tried to compromise and solve this article's text issues, but Attic Salt just display complete unwillingness to even state what the actual problem is - other than to disagree with it. It is clear the User is wishing to ignore WP:GF, espcially in light of an explaination of difficulties with plasma as a definiton. Why even bother fixing it when your not willing to engage in the process? Attic Salt claims "Nothing wrong with getting other editors to look this over." Yet they are unwilling to to contribute via normal process of consensus, and hasn't even bothered to say why it is wrong.

After a similar attempt[39] (+false accusation[40]) by User:141.131.2.3 followed by my own responses under Talk:Plasma (physics)#WP:OWN violation, shows the behaviour displayed is suspicious and warrents scrutiny.

Honestly, if anything that needs fixing is the Main article under Plasma (physics)#Properties and parameters#Definition, where the text is frankly just very confused set of words. It in fact defines a 'plasma stream' but says nothing really defining plasma itself. How are you supposed to summarise his in an Introduction if it is not the main document. Much of this appears on the "Wikipedia:Good article reassessment/Plasma (physics)/1" here[41], after which I fixed up the Introduction.)

For these reason this Rfc should be immediately closed. Arianewiki1 (talk) 01:08, 7 October 2017 (UTC)

It's clear from their contributions (at least one edit every day since 29 September 2017, which is when they started the #Working on the lede. thread above) that Attic Salt (talk · contribs) has neither left nor retired. Perhaps their use of the word was not in accord with the understanding described at Template:Retired - after all, they've been here less than three weeks and can't be expected to have a full knowledge of our terminology, which at times can be quirky. Maybe they meant "left" in the sense of "I'm just off to buy some groceries, I'll be editing again once I've had a coffee". Maybe they meant "retired" in the sense of "I'm old enough to have given up full time work and can now dedicate spare time to things that do not pay a salary, like Wikipedia". Anyway, speaking personally, I don't consider somebody to be truly retired from Wikipedia until they have shown no activity of any kind for a significant period - a month or more. When somebody claims (correctly or not) to be retired, I don't go around closing discussion threads that they opened; these discussions may be of use to the general community. --Redrose64 🌹 (talk) 07:36, 8 October 2017 (UTC)

@Redrose64: Umm. Explain this edit, please. [42] Thanks. Arianewiki1 (talk) 08:56, 8 October 2017 (UTC)

@Redrose64: Did you read my reasoning here[43]? /no mention of retirement there. Also be aware of this current WP:ANI.[44] Thanks. Arianewiki1 (talk) 09:05, 8 October 2017 (UTC)

• I just filled Wikipedia:Administrators'_noticeboard/Incidents#Repeated_closure_of_RfC_by_involved_editor_.2B_alteration_of_others.27_talk_page_comments. Tigraan^{Click here to contact me} 10:11, 8 October 2017 (UTC)

I closed this. Attic Salt (talk) 11:12, 8 October 2017 (UTC)

@Attic Salt: "I closed this" Meaning what precisely? The Rfc has to be closed in a particular way. Do you mean you don't want to engage in this debate or something else? Arianewiki1 (talk) 00:05, 9 October 2017 (UTC)

As the person who opened the request for comment, I am permitted to close the request as per [45]. I did this to try to reduce the heat that the request seems to have generated. At the same time, I think we got some useful input, even if the request did not meet everybody's technical expectations (apologies for that). I do not want to imply that discussion on how to improve the lede (or the article) should necessarily cease. Attic Salt (talk) 00:11, 9 October 2017 (UTC)

@Attic Salt: Ah I see! You need to formally close it, which is done like this {{closed rfc op|result=Reason...}}, and is placed at the top of the initial title. Please, if you are unsure, just ask another User or pose the questions if you are unsure. Like me, most editors here are more than willing to help if they can! Arianewiki1 (talk) 00:45, 9 October 2017 (UTC)

Um, when I read [46], it says the procedure you suggest is not actually required. I will, however, try to do it now. — Preceding unsigned comment added by Attic Salt (talk • contribs) 00:50, 9 October 2017 (UTC)

*Several editors suggest a reworking of the lede to have a defining sentence: 141.131.2.3 (see discussion above in WP:OWN violation), Attic Salt, William Avery (who cited Wikipedia guidelines for the first sentence).

• Other editors made comments suggesting that they sympathize with the lede having a defining sentence, though it might be technically difficult to attain an ideal definition: Nerd1a4i, VQuakr, Tigraan.
• Only two editors were against the lede having a defining sentence: Arianewiki1 (who "strongly" opposed the suggestion, but he/she might have slightly moved on this), Cwmhiraeth (who felt that a version of the lede (not sure which version) already had sufficient information).

So, my summary of the request for comment: mostly in favor of a defining sentence appearing in the lede. I hope that helps. Attic Salt (talk) 12:52, 8 October 2017 (UTC)

Suggest closure Without a specific version of the entire lede paragraph being proposed, a !vote is not particularly helpful. I feel the current version at [47] is an improvement over the status quo ante bellum at [48], but neither is perfect. Ideally, in a new thread, people can focus on the merits of specific changes to the lede, rather than on the motives of the authors of those changes. power~enwiki (π, ν) 17:04, 8 October 2017 (UTC)

For some reason, the blue box extends into the next sections of discussion. If anyone can fix this, thanks. Attic Salt (talk) 00:55, 9 October 2017 (UTC)

Close I have already said when I formally closed this "If an Rfc is still required, it should state a valid question that meets the guidelines." You can't expect editors to debate an issue, when the posed question was already negative to begin with, I.e. "Should the first paragraph of the lede contain a definition of "plasma"?" It already does define 'plasma', making the statement false.

As for me, I am facing two WP:ANIs at the moment, instigated by Tigraan and VQuakr. The whole failure IMO here is trying to sort out multiple unrelated issues, when there is no defined purpose. I was responsible for my initial wording of this Introduction, and I have explained why I've done it in the way that I have. It was not decided by a whim. If there is a better way of express it, please specifically state it, then we can sort out the minutia and wording. Thanks. Arianewiki1 (talk) 01:01, 9 October 2017 (UTC)

Oddly, Arianewiki1 inserted a comment after the closure box was put in place. I will refrain from undoing it. In this comment, he/she suggests that the the first paragraph had a definition of plasma when the RFC was initiated. For reference, here is the state of the article just prior to the RFC: [49]. There, in the first paragraph, one can find only vague assertions that plasma is one of the four states of matter, that it doesn't exist on Earth under "normal surface conditions", etc. But what is being discussed, "plasma", is not defined. With such an opening paragraph, the reader would be left confused as to what is even being discussed. Seeing this, and noting that Arianewiki1 was opposed to changing the first paragraph of the lede (see his/her many and long comments), I opened the RFC. Why we still are going around on this is, to me, a mystery, but what we have now in the first paragraph of the lede is a modest improvement. Attic Salt (talk) 01:27, 9 October 2017 (UTC)

Simple explanation. I tried to post my reply, that was during the time you closed the Rfc, and the conflict prevented me from posting it in time. Do I delete it or keep it - especially with two ANI's I'm fighting in between? Rfc is closed. Let's move on. Arianewiki1 (talk) 03:46, 9 October 2017 (UTC)

@Arianewiki1: In response to your question of 08:56, 8 October 2017 (UTC): Attic Salt (talk · contribs) is perfectly within their rights to add a {{retired}} to their user page should they so wish, it's also their right to remove it just over four hours later if that is also what they wanted to do. I see no need for me to explain those actions. You, however, should not have re-added that template after Attic Salt removed it themselves. User pages are not discussion pages: if you wanted to ask "meaning what???/" you should have done so at User talk:Attic Salt. --Redrose64 🌹 (talk) 07:46, 9 October 2017 (UTC)

@Redrose64: Sorry, I'm not going to bite on this one. Much of this you say isn't factual from my point of view. Where exactly is 08:56, 8 October 2017 (UTC) please? (You should have post this on my Talkpage.) As for the "meaning what???/", was meant to placed that on the Talkpage. Considering tghe rapid edits at the time it was hard to keep up. I was reponding to statement "Momentarily unretired so that I might contact a CU." I still don't know what that means.

Thanks for another 'global pasting' when I'm already under scutiny of two ANI's - if that's not pressure enough. Arianewiki1 (talk) 09:10, 9 October 2017 (UTC)

08:56, 8 October 2017 (UTC) is the timestamp of one of your posts above. I'm not going to post on your talkpage concerning a matter already under discussion above: that would split it into WP:MULTIple fragments and makes it much harder to follow. To your claim of two ANIs: I am only aware of one - Wikipedia:Administrators' noticeboard/Incidents#Repeated closure of RfC by involved editor + alteration of others' talk page comments. No other current ANI thread mentions you, nor do any in recent archives (965 and 966, which between them go back to 18 September 2017, some days before Attic Salt made their first edit). If you posted on a user page instead of a user talk page, you should have self-reverted and then posted in the proper place. --Redrose64 🌹 (talk) 23:11, 9 October 2017 (UTC)

@Redrose64: "See 3RR here Wikipedia:Administrators' noticeboard/3RRArchive352#User:Arianewiki1 reported by User:VQuakr (Result: ). As for "If you posted on a user page instead of a user talk page, you should have self-reverted and then posted in the proper place." Yes, but I didn't respond quick enough when others complained, and I reverted it when I realised it. The link explains it. Thanks. Arianewiki1 (talk) 01:49, 10 October 2017 (UTC)

That's WP:ANEW, not WP:ANI. Different board, different scope, different (potential) consequences. --Redrose64 🌹 (talk) 10:32, 10 October 2017 (UTC)

• NOTE: I just now removed the "close" by a participant, per WP:RFCEND. Since there does not seem to be a real consensus in terms of bolded Yes/No or Support/Oppose !votes, just let the RfC run for 30 days. Then let an uninvolved person close it, if a close is necessary. It might be more efficient to have a Survey section and a Discussion section, to separate Yes/No !votes from endless threaded discussion. One last comment: The RfC question is neutral and brief, so it follows standard WP:RFC format. There isn't really a need to determine the exact wording of the "definition"; the question is merely whether there should be a definition of plasma in the first paragraph of the lede. Softlavender (talk) 06:47, 10 October 2017 (UTC)

@Softlavender: I closed the Rfc because of the wrongly word statement. power~enwiki suggests closure. The instigator of the Rfc wants to close it. Then when things begin to settle down it is open again! I think you have misinterpreted what has happened here... Attic Salt made the last closure not me! !Arianewiki1 (talk) 07:38, 10 October 2017 (UTC)

Please read WP:RFCEND. So far there have been nine participants in the RfC, and no real consensus. The OP therefore cannot withdraw the RfC, and it cannot be closed since there is no consensus about anything. If he would like to comment that he thinks the opening paragraph is currently fine or improved, he is free to comment to that effect in the discussions here in this RfC, but he can't close it. If you or anyone else no longer wants to discuss matters in this RfC discussion, that's fine; there is no requirement for participation. And as I mentioned above, there is nothing "wrongly worded" about the opening question. Please learn to indent your talkpage posts with the proper number of colons so that they nest correctly under the post you are replying to. I have done that for you above. Softlavender (talk) 07:55, 10 October 2017 (UTC)

@Softlavender: I've read this. The WP:RFCEND says: "1) The question may be withdrawn by the poster. In this situation, the editor who started the RfC should normally be the person who removes the template." Attic Salt was the poster, and withdrew it.[50] There was a problem with a missing end tag, which was fixed. I did nothing but assist User:Attic Salt here, but didn't close it.

Why are you dragging me into this when the last closure was not even made by me? The earlier issues happen 3-4 days ago, and although the problem is confusing, most have moved on. I've apologised where I could. What the proble now? Arianewiki1 (talk) 08:26, 10 October 2017 (UTC)

I'm not "dragging you into" anything. I reverted the close by a participant. The participant, in this case the poster, did not "withdraw" the RfC, he closed it with an outcome that was not the actual consensus. Please also read the actual wording of WP:RFCEND, that you have only partially quoted: "The question may be withdrawn by the poster (e.g., if the community's response became obvious very quickly)." (bolding mine) Nothing like that has occurred here. There have been nine participants so far, and no real consensus. Softlavender (talk) 09:26, 10 October 2017 (UTC)

@Softlavender: Honestly, have you read the WP:RFCEND that you keep citing? The question may be withdrawn by the poster - no conditions on that that I can see; if the poster wishes to withdraw, that's that according to RFCEND. The poster attempted to withdraw the question and gave a coherent rationale for that. Somewhat less weighty in this case, but still worth considering, The RfC participants can agree to end it at any time, and one of them can remove the rfc template. We can argue about how much agreement is an agreement, but there is support for an "abort" close from at least three of the few participants here and I don't think anybody can deny that this RfC is significantly flawed. There is nothing wrong with an RfC restart and it happens with some frequency. We learn from the mistakes made in the first attempt, and we avoid repeating them in the second. Significantly flawed RfCs do not benefit the encyclopedia. (There is no requirement that an aborted RfC be followed immediately by a second attempt on the same issue, by the way.) I believe this argument outweighs "RFCs generally run for 30 days". ―Mandruss ☎ 08:29, 10 October 2017 (UTC)

Please read the full wording of that part of WP:RFCEND, that you have only partially quoted: "The question may be withdrawn by the poster (e.g., if the community's response became obvious very quickly)." (bolding mine) Nothing like that has occurred here. There have been nine participants so far, and no real consensus. Not to mention the poster did not "withdraw" the RfC, he closed it with a stated consensus which does not match the varied comments of the nine different participants. If he wants to withdraw it, he can simply withdraw it, but he can't close his own RfC, and since there is no consensus among all nine participants to close, no participant should close it. There's also no need to close if discussion simply dies out. All RfCs do not require closure. Softlavender (talk) 09:26, 10 October 2017 (UTC)

Ok, I may have misinterpreted the poster's comments here. If so, I apologize to you before wiping the egg off my face. Attic Salt, if what Softlavender says about your close is correct (and I can't find your close attempt in all this mess), it was improper. If you wish to withdraw on the basis of flaws, do so without stating a consensus either way; a close withdraw statement as simple as "Withdraw as significantly flawed." would be sufficient in my opinion; no need to enumerate said flaws in the close withdraw. I don't think there is enough agreement to justify close ending the RfC solely on the basis of WP:RFCEND item 2. ―Mandruss ☎ 09:48, 10 October 2017 (UTC)

And I'm apparently being too loose with the use of the word "close", as it implies assessment of consensus per RFCEND. Fixed via strikethroughs and updated my vocabulary. ―Mandruss ☎ 10:18, 10 October 2017 (UTC)

• NOTE: Once again, I have reverted the close by a participant, per WP:RFCEND. NIne people have participated in the RfC, and there does not seem to be a real consensus in terms of bolded Yes/No or Support/Oppose !votes. Therefore it is best for the RFC to run the standard 30 days, and then let an uninvolved person close it, if a close is necessary. Or just die out. It might be more efficient to have a Survey section and a Discussion section, to separate Yes/No !votes from endless threaded discussion. One last comment: The RfC question is neutral and brief, so it follows standard WP:RFC format. There isn't really a need to determine the exact wording of the "definition"; the question is merely whether there should be a definition of plasma in the first paragraph of the lede. Softlavender (talk) 03:00, 12 October 2017 (UTC)

Closing this Rfc once and for all... @Softlavender: @Attic Salt: @Arianewiki1: @Nerd1a4i: @Cwmhiraeth: @Tigraan: @Redrose64: @Power~enwiki: @Mandruss: @VQuakr: Based on the persistent reverts by Softlavender to close this Rfc, has this Rfc discussion been finished under the rules of WP:RFCEND? Note: Whilst Softlavender maybe dancing on the closure rules here, it is clear from the invalid premise of this Rfc (which cannot be answered, because the first paragraph already does contain a valid definition), that the actions of Softlavender has only undermined WP:Commonsense and editor's needed WP:GF. (I refer Softlavender specifically to WP:What "Ignore all rules" means#Diagram and flowchart as a start.) Worryingly, using such Rfc actions in the future, especially by any newbee or IP, could easily use the rules as a potent weapon to inhibit or stall editing. In this case, despite no actual consensus, nor a valid question, the original text in this has just favoured the Rfc instigator, even upon stated objections, actual explanation, nor logical argument. IMO, the some WP:RFCEND needs to be rewritten to give more autonomy to those participating in them. I have now given a formal explanation here[51] in the newest Rfc, which those interest should either refute or incorporate in the Introduction. Arianewiki1 08:06, 12 October 2017 (UTC)

For reference, [52], prior to the initiation of this RFC, the first paragraph did not contain a definition of "plasma", and Arianewiki1 strongly opposed it having one: [53]. Attic Salt (talk) 08:25, 12 October 2017 (UTC)

Arianewiki1, there was nothing whatsoever "invalid" about this RfC. At the time it was posted, the first paragraph of the article did not contain a definition of the word plasma: [54]. Therefore the RfC was correctly worded as "Should the first paragraph of the lede contain a definition of 'plasma'?" [55] There is no consensus in this RfC. It should not be closed by a participant. If you and others no longer wish to comment here, participation is not mandatory. If the filer wishes to withdraw the RfC, they may, but they should not close it with an assessment of consensus. Nor should any of the participants, because there have been nine participants and there is no consensus. Arianewiki1, please learn to format your posts correctly, and use the Preview button to check before you save your posts. I have corrected your post above. Softlavender (talk) 08:29, 12 October 2017 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

The metaphor with jelly

I’d like to suggest that the first couple sentences of the History section, which presently reads:

“The word plasma comes from the Ancient Greek πλάσμα, meaning "moldable substance"[14] or "jelly"[2], whose usage describes the behaviour of the ionised atomic nuclei and the electrons within the surrounding region of the plasma. Very simply, each of these nuclei are suspended in a movable sea of electrons.”

… be adjusted to more fully encompass the collective behaviour quality summarised by the following citations.

Drummond, in the introductory chapter of his book, states that plasma oscillations, observed by Tonks and Langmuir (1929) exhibited oscillatory behaviour (a collective behaviour) similar to the oscillations of a jelly plasma, p. 1: [56]

Inan and Gołkowski make a similar statement , p. 2: [57]

Chen, uses the jelly metaphor to describe a blob of plasma (again, collective behavior), page 205: [58]

In light of this, and to initiate discussion, I propose the following possible text, which might be reasonably altered or improved upon by other editors:

“The word plasma comes from the Ancient Greek πλάσμα, meaning "moldable substance"[14] or "jelly"[2]. This metaphorical name can be traced to observations made by Tonks and Langmuir in 1929 that oscillations in ionised gas resemble oscillations of jelly. [59]

Thanks, Attic Salt (talk) 13:33, 21 October 2017 (UTC)

Great. Add that to the article, but in case you are thinking of it, this has very little use in the Introduction. Again we see the abject failure that the introductory text is aim to the general reader and simply summarises the main body of the article. Hitching onto "collective behavior", when this is only a single parameter about plasma - and relies on a whole lot of assumed knowledge (historical and fact) and trivial. e.g. It is like defining Cathode rays when they are better known as electrons. Arianewiki1 (talk) 00:10, 22 October 2017 (UTC)

Actually, this does look like personal research WP:OR and WP:SYNTHESIS, and does not necessarily tell the full story. e.g. Experiments done by these researchers used mercury arc plasmas under vacuum in glass jars, whose reaction created a uniform glow that looked like jelly in a mold. It only pulsated when the current was adjusted to show the degree of ionisation. Sorry, it just looks like massaging information to satisfy 'collective behaviour' and satisfying / reinforcing their own arguments. Arianewiki1 (talk) 02:39, 22 October 2017 (UTC)

Actually, what I've proposed is a summary explanation given (mostly) in the Drummond source (and which appears to be confirmed by the other sources I've cited); I've linked the sources, please consider reading them if you haven't already. The property of simply filling a mold, as you describe, is the property of a gas, not just a plasma; and the property of giving off light is not what we normally associate with "jelly". If you feel the suggested text needs adjustment, then please propose something that is sourced. Thanks. Attic Salt (talk) 12:59, 22 October 2017 (UTC)

Reading Goldstone, R.J., Rutherford, P.H., "Introduction to Plasma Physics", pg.2 (1995), where it says "Irving Langmuir, the Nobel laureate who pioneered the scientific study of ionized gases, gave this new state of matter the name ‘plasma’. In greek means ‘moldable substance’ or ‘jelly’, and indeed the mercury arc plasmas with which he worked tended to diffuse throughout their glass vacuum chambers, filling them like jelly in a mold." (This reference is the standard text in teaching the subject.) Saying " The property of simply filling a mold, as you describe, is the property of a gas, not just a plasma." misses the point, because that is not what Langmuir is talking about at all.

Again, this does look dangerously like personal research WP:OR and WP:SYNTHESIS, deliberately linking "moldable substance" or "jelly" to oscillations, as to only support the analogy of "collective behavior" once stated by Langmuir in 1929.

What you are missing here, is that this only applies to plasma in certain circumstance eg.'aurora' 'magnetosphere', and does not apply say, Sun's corona or fusion. I.e. Irving Langmuir paper is entitled "The Interaction of Electron and Positive Ion Space Charges in Cathode Sheaths." Considering the range of plasma related articles and the diversity of parameters discussion within the main body of Plasma (physics), you are complicating this too much, and forgetting who is reading it. Arianewiki1 (talk) 23:34, 22 October 2017 (UTC)

At the risk of being accused of performing original research, and since there seems to be some contradictions (or misinterpretations, possibly on our parts) of what is said in the book by Goldstone and Rutherford and the books I've already linked above, I chased down the 1929 paper by Tonks and Langmuir (1929); [60]. This paper is entitled "Oscillations in ionized gases". Here, on page 196 (the second page in the pdf file), Section A, they describe oscillations in the density of electrons relative to a rigid jelly of ions, on the next page, they dub these density oscillations "plasma-electron oscillations". I'm happy to accept this, and even see a quoted taken directly from the article to help clarify this issue. Arianewiki1, do you find this acceptable? I hope so. And thank you. Attic Salt (talk) 02:19, 23 October 2017 (UTC)

I also note that Langmuir, in his 1928 paper, also entitled "Oscillations in ionized gases", uses the word "plasma", though he does not explain why he uses this word, he just describes the medium as a "region of balanced charges of ions and electrons" (p. 628): [61]. In this paper, there is no specific mention of "jelly", though Langmuir proceeds to discuss the medium as a "continuum" of "positive electricity" in which there is a "free distribution" of electrons that oscillate. I have not found a mention of "jelly" prior to Tonks and Langmuir (1929), but it might be out there. For now, I'm seeing that none of the secondary sources cited in this discussion give a clear discussion on this issue of terminology. Attic Salt (talk) 13:26, 23 October 2017 (UTC)

Okay, in the book by Merle Hirsh: [62], Langmuir introduced the word "plasma", according to his colleague, Tonks, in analogy with blood plasma. Hirsch suggestes, furthermore, that Langmuir's use of the word is related to the ability to "molded" (oddly, no source is cited for this speculation). So, perhaps finally, we can understand that the metaphor is with blood itself. Attic Salt (talk) 13:54, 23 October 2017 (UTC)

The "blood" metaphor was, some time ago, in this article: [63], only to be subsequently removed with this edit: [64]. Attic Salt (talk) 14:13, 23 October 2017 (UTC)

I have obtained a copy of the 1967 paper The Birth of "Plasma" by Lewi Tonks,Tonks, Lewi (1967). "The birth of "plasma"". American Journal of Physics. Vol. 35. pp. 857–858. doi:10.1119/1.1974266. a close colleague of Langmuir. In this paper, Tonks recalls the moment that Langmuir started using the word "plasma" to describe the "gaseous electronic" experiments on which both Langmuir and Tonks were working in the last 1950s. Tonks says that, subsequently, a number of authors have guessed at the origin of the Langmuir's use of "plasma" -- that some of these guesses are more "colorful and vivid" than based in actuality. Tonks says that he thought that Langmuir used the word "plasma" in analogy to blood -- though, curiously, Tonks does not give (at least to me) a clear explanation for this analogy. Tonks says that Langmuir was certainly not referring to the "oscillatory characteristics" of plasma, nor was he referring to "cellular jelly or protoplasm". These assertions are difficult to reconcile with some of the textbooks cited in this discussion and in the Plasma (physics) article itself; notably both the book by Goldstone and Rutherford and the book by Drummond appear to continue the "guesses" that Tonks criticised in 1967. I propose that we add a footnote on this, citing the paper by Tonks. Attic Salt (talk) 23:46, 26 October 2017 (UTC)

Utter rubbish. This is certainly WP:SYNTHESIS and WP:OR. I propose you've now crossed over into pushing an undisclosed agenda, likely plasma cosmology, especially in light of the debacle on demanding a 'definition of plasma which is ultimately bogus and disruptive. Why else would anyone create this utter fiction, especially for a deemed 'newbee'? Muddying the waters here is really reprehensible. Arianewiki1 (talk) 08:00, 27 October 2017 (UTC)

Here's another paper that gives more clarity to the blood metaphor, this one is by Harold Mott-Smith, also a colleague of Langmuir:Mott-Smith, Harold M. (1971). "History of "plasmas"" (PDF). Nature. Vol. 233. p. 219.

Arianewiki1, you might be interested in this article on the "quasi-history" sometimes presented in physics textbooks:Whitaker, M A B (1979). "History and quasi-history in physics education-part I". Physics Education. Vol. 14. pp. 108–112. If we were unaware of some of the details of how plasma came to be called "plasma", I think we can be happy when we learn something new. Attic Salt (talk) 17:04, 27 October 2017 (UTC)

I have added a short summary to the article of the accounts by Tonks and Mott-Smith (both given in reliable sources). I also added a link to the chapter in the Hirsh reference (which was already cited in the article), since this quotes Tonks. Thanks. Attic Salt (talk) 13:22, 28 October 2017 (UTC)

"Arianewiki1, you might be interested..." Nope. You've defied WP:GF and shown your own colours here. This is plainly WP:OR. Having a revealed agenda shows your insincerity here. Arianewiki1 (talk) 08:31, 29 October 2017 (UTC)

Plasma approximation (and confusing text found in that section)

A sentence in the section on the "plasma approximation" presently reads:

"The plasma approximation is valid when the number of charge carriers within the sphere of influence (called the Debye sphere whose radius is the Debye screening length) of a particular particle is higher than unity to provide collective behavior of the charged particles. The average number of particles in the Debye sphere is given by the plasma parameter, Λ."

To me, this is confusing. For one thing, the notion of a sheath has not, at this point in the essay, even been mentioned. Perhaps this is reasonable, but there is no explanation as to why the number of particles within the Debye sphere must be greater than "unity" (that what the sentence says). I think it would normally be expected that the number of shielding particles be quite a bit more than "unity" if only for statistical reasons. I propose that this sentence be simplified, slightly, to read:

"The plasma approximation applies when the plasma parameter, Λ, representing the number of charge carriers within a sphere (called the Debye sphere whose radius is the Debye screening length) surrounding a given charged particle is sufficiently high so as to shield the electrostatic influence of the particle outside of the sphere. This short length-scale shielding permits collective behavior on length scales longer than the Debye radius."

In writing this, I hope that I am not accused of performing original research or synthesis! Thank you. Attic Salt (talk) 00:02, 30 October 2017 (UTC)

With no comments or suggestions after 6 days, I went ahead an changed the text. Thank you. Attic Salt (talk) 14:21, 5 November 2017 (UTC)

Attic Salt I always appreciate anyone who wants to make a passage in an article clearer and more concise. I know very little about physics, but I understand enough to know whether something is clearer or less clear, and your wording seems clearer. May I suggest a few changes?

(a) In the parenthetical phrase after "within a sphere", remove "whose radius is the Debye screening length". It unnecessarily lengthens (and thus complicates) the sentence. You could link "Debye screening length" to Double layer (surface science), the article to which a search for "Debye screening length" leads. You could write the link as a piped link, with "Debye screening length after the pipe. Readers who want to know more about "Debye screening length" can read the linked article.

(b) Add a comma after "charged particle". This is the end of a parenthetical phrase that begins "representing".

(c) Remove "so" after "sufficiently high". It is not necessary since you have be ("is") and the adverb "sufficiently": "...is sufficiently high as to shield...". To use "so as to shield", you would have to change the wording so you have an action verb instead of "is" + adjective ("high"), something like, "when the plasma parameter, Λ,... [does something] so as to shield..." I don't think such a change is necessary since, without that "so", it reads well.

(d) With regard to the phrase, "surrounding a given charged particle", it is not completely clear whether this refers to any charged particle, anywhere, or specifically to a charged participle within the sphere (referring, I am assuming, to the same sphere mentioned earlier in the phrase "within a sphere"). Would it makes sense to add the phrase "within the sphere" after it? Best regards, a non-expert in physics,  – Corinne (talk) 00:30, 6 November 2017 (UTC)

Corinne Thank you very much for this helpful input. I will mull all this over when I have a chance (very soon). Attic Salt (talk) 00:54, 6 November 2017 (UTC)

In réponse to Corinne's suggestion that the discussion of Debye screening be reduced, I note that both Chen (p. 8) and Goldston and Rutherford (p. 14) introduce the material that is in the "Bulk interactions" section of this article before they introduce the content in the "Plasma approximation". This allows for a discussion of Debye screening first, then plasma parameter second. So, working with both of these sections, but in reverse order as presently found in this article, could help with the economy of presentation. Thoughts? Attic Salt (talk) 14:45, 6 November 2017 (UTC)

You must be typing on a French keyboard. I see "In réponse". ;)  – Corinne (talk) 15:25, 6 November 2017 (UTC)

That's a fancy response. ~Kvng (talk) 15:50, 9 November 2017 (UTC)

RfC on the lede, started anew

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

Which version of the first paragraph of the lead (in particular the first sentence) is best? Tigraan^{Click here to contact me} 09:10, 11 October 2017 (UTC)

Context

See page discussion above. I would have thought power~enwiki's version would attract consensus, but at least two editors disagree. I am thus rebooting the previous RfC but with a proper procedure.

Options

Version 1: (added 09:10, 11 October 2017 (UTC))

Plasma (from Ancient Greek πλάσμα, meaning "moldable substance") is a state of matter which can be loosely defined as an ionised gas, though partially ionised plasmas also exist. This ionization makes the plasma affected by electromagnetic fields, which heavily influence how the plasma behaves. It is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s. Unlike the other three states of solid, liquid, and gas, plasma does not freely exist on the Earth under normal surface conditions, and can only be artificially generated by heating neutral gases or by subjecting that gas to a strong electromagnetic field.

Version 2: (added 09:10, 11 October 2017 (UTC))

Plasma (from Ancient Greek πλάσμα, meaning "moldable substance") is a state of matter in which an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter. It is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s. Unlike the other three states of solid, liquid, and gas, plasma does not freely exist on the Earth under normal surface conditions, and can only be artificially generated by heating neutral gases or by subjecting that gas to a strong electromagnetic field.

Version 3: (added 05:27, 12 October 2017 (UTC)}

Plasma (from Ancient Greek πλάσμα, meaning "moldable substance" or "jelly") is one of the four fundamental states of matter, while the others are solid, liquid, and gas. Unlike these three states of matter, plasma does not naturally exist on the Earth under normal surface conditions, and can only be artificially generated from neutral gases. The term was first introduced by chemist Irving Langmuir

Plasma and ionised gases have unique properties and display behaviors unlike those of the other states, although the true technical transition between the two is mostly a matter of nomenclature and subject to interpretation. It can simply be considered as a gaseous mixture of negatively charged electrons and highly charged positive ions, being created by heating a gas or by subjecting gas to a strong electromagnetic field. However, true plasma production is from the distinct separation of these ions and electrons that produces an electric field, which in turn, produces electric currents and magnetic fields.

Based on the surrounding environmental temperature and density either partially ionised. or fully ionised forms of plasma may be produced. Partially ionised plasma is popularly understood, for example, as neon signs or lightning storms, while more fully ionised plasma is associated with the interior of the Sun, the solar corona.

Survey

• 2 per below. Tigraan^{Click here to contact me} 09:10, 11 October 2017 (UTC)

• 3 per below. Arianewiki1 (talk) 04:16, 13 October 2017 (UTC)

• 2. The first sentence should say what plasma is. Option three skirts the issue. Sure plasma is a state of matter, but that barely tells me anything ("Plasma is an English word placing between plasm and plasmablast in the dictionary" is also true, for example). I have no objection to including some of the other text in #3, e.g. where plasma can be found in nature, into the lede, but I dislike the first paragraph. As for #1, I prefer #2 because I do not expect to see the word 'loosely' in the first sentence - it sounds like the author has already given up on explaining what plasma is, in the very first sentence. Banedon (talk) 04:46, 19 October 2017 (UTC)
• 2. As per sources (Chen, Friedberg) cited in article. Option 3 does not define plasma in first paragraph and meanders. Attic Salt (talk) 09:54, 20 October 2017 (UTC)

• Alternative summoned by bot. I suggest a simple rewrite to the current opening sentence. I think we want to have the first sentence state that plasma is one of the four states of matter, yet we don't need to name the other three in the first sentence, since there's a Wiki-link, and the other three states are subsequently listed.

Plasma (from Ancient Greek πλάσμα, meaning "moldable substance", is one of the four states of matter, and resembles an ionised gas, though partially ionised plasmas also exist.

• 1 is concise and clear. (Some tangential comments on 2 and 3 below.) Maproom (talk) 07:00, 25 October 2017 (UTC)
• 2 is the best starting point. Further improvements are possible. ~Kvng (talk) 14:09, 25 October 2017 (UTC)
• ""2"" is a better description, although I do have a niggle over its commonality on earth's surface. After all, lightning and fire are not uncommon

Wzrd1 (talk) 04:11, 31 October 2017 (UTC)

Discussion

In general, the first sentence should say what plasma is (power~enwiki). Version #1 fails on that point: "which can be loosely defined as" is verbose, it should already be avoided in a perfectly-written article but even more so in the lead. However, "plasma is ionised gas" is outright misleading and thus cannot be used. Version #2 has the advantage of being concise and true. Tigraan^{Click here to contact me} 09:10, 11 October 2017 (UTC)

I don't like the phrase "though partially ionised plasmas also exist" being in the first sentence, re-wording it could probably convey the same knowledge in a clearer way. I want to wait for a proposal endorsed by Arianewiki1 before commenting further. power~enwiki (π, ν) 14:34, 11 October 2017 (UTC)

Comparing the different versions, it might confuse the discussion that option 3 has three paragraphs, while 1 and 2 only have one. I suggest that the last two paragraphs of option 3 be removed. Attic Salt (talk) 12:58, 12 October 2017 (UTC)

Well, maybe adding all the paragraphs to version 1/2 is better. I did not want to do that because the focus is really on the first two paragraphs when drafting, but since Arianewiki1 added #3 with multiple paragraphs (and the bottom paragraphs differ from version #1/2) it may be best. Tigraan^{Click here to contact me} 15:06, 12 October 2017 (UTC)

Attic Salt whole argument has been based on the wrong premise that the first line must state what definitively was 'plasma' is. It is not the case. Please define what you consider plasma, and show where this argument is wrong or flawed.[65]

Frankly, you ask the impossible, and the first sentence/paragraph of #1 and #2 are incomplete and/or incorrect. Comprehensibility is far more important than some arbitrary narrow structural definition.

You said Attic Salt at the very beginning of this storm on 03:39, 29 September 2017 (UTC)

"Perhaps we can use something like "Plasma is a special kind of ionized gas and in general consists of positively charged ions, electrons, and neutrals." -- Taken largely from this intro article: [7] (not my definition). Note that some of this appears in the second paragraph, so we might rearrange material from there. Thoughts?"

Now actually reading the article, in doesn't quite say this at all. These qualifier also appeared:

"(Under special conditions, plasma may also contain negative ions. But here we will not discuss this case further. Thus in what follows the term ‘ion’ always means ‘positive ion’.)

"We call an ionized gas ‘plasma’ if it is quasi-neutral and its properties are dominated by electric and/or magnetic forces. Owing to the presence of free ions, using plasma for ion sources is quite natural. For this special case, plasma is produced by a suitable form of low-pressure gas discharge. The resulting plasma is usually characterized as ‘cold plasma’, though the electrons may have temperatures of several tens of thousands of Kelvins (i.e. much hotter than the surface of the Sun), while ions and the neutral gas are more or less warm. However, owing to their extremely low mass, electrons cannot transfer much of their thermal energy as heat to the heavier plasma components or to the enclosing walls. Thus this type of cold plasma does not transfer much heat to its environment and it may be more exactly characterized as ‘low-enthalpy plasma'.''"

On pg.1 It also says; "Owing to the presence of free charge carriers, plasma reacts to electromagnetic fields, conducts electrical current, and possesses a well-defined space potential."

On pg.5 it says: "2.4 Plasma as a gas A gas is described adequately by single-particle properties averaged over the particle distribution functions and parameters like pressure, temperature and density, which can be correlated to those averages, as we know from kinetic theory. Plasma kinetic theory is classical Boltzmann statistics, if the distance between particles (electrons, ions, neutrals) is sufficiently large (classical plasma)... Otherwise plasma is degenerate."

Then on pg.6 "Plasma with large plasma parameter is ‘non-ideal’ or ‘strongly coupled classical plasma’. ... Thus non-ideal classical plasma is very cold and very dense. In such a case, correlations between the plasma particles may become important. Under laboratory conditions, such correlations can be observed in dusty plasmas, where dust particles sometimes adjust themselves into regular structures.'"

• Version 1 says; "...is a state of matter resembling an ionised gas," This is wrong, as the plasma is defined by the degree of ionisation, but you can't have plasma state until sufficient electrons have been stripped to create an electric current (else it is only ionised gas) (separation), then you also have to consider the local electron density and temperature (eg. cold and hot plasmas). Yet, when we describe an ions, e.g. FeII, FeIII, FeIV, onto say, FeXX in the Sun's corona, so when does this ionised gas all of a sudden become a plasma? As yet, the definition depends on who you talk too, and what field is being investigated. I.e. Plasma televisions or stars, for example.

• Version 2 particularly saying "Plasma...is a state of matter in which an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter." when it is not entirely true and at best is misleading It is not just the field production defining a plasma. (Also the statements above by Attic Salt's statement is not absolutely true, and I believe shows obvious general misunderstandings. No offense.) Also wrong is the stripped electrons that forms the fields, it is the atomic nuclei that constitute the plasma. No mention of the separation, no mention of the degree of ionisation, no mention induced plasma by a strong electromagnetic field (cold plasma.) If some one was my student, the central question would be: "Name all the circumstances when ionised gas become plasma?"

The only solution to solve this is the qualifier [#3 Para.3]: "Plasma and ionised gases have unique properties and display behaviors unlike those of the other states, although the true technical transition between the two is mostly a matter of nomenclature and subject to interpretation." True.

Version #3 in the third paragraph is absolutely necessary, as it has the qualifier: "Based on the surrounding environmental temperature and density either partially ionised or fully ionised forms of plasma may be produced." This is reinforce with actual examples: "Partially ionised plasma is popularly understood, for example, as neon signs or lightning storms, while more fully ionised plasma is associated with the interior of the Sun or the solar corona." Versions #1 and #2 say nothing of this.

Lastly, Version #1 and #2 are too complex language, fails to summarize the main body's text, and worst lacks or ignores many key elements that define 'plasma.' I.e. Source, density, temperature

Hence, Version #3, (perhaps slightly further restructured) is the better option.

Either refute my arguments, define a paragraph that summarises these central facts, or accept the longer original cited text so the average reader can at least understand it. Plasma (physics) is not simple to just compress into some arbitrary sentence or two. Arianewiki1 (talk) 04:12, 13 October 2017 (UTC)

Arianewiki1, while it is true that Plasma (physics) is not simple to just compress into some arbitrary sentence or two, it is the case of pretty much any topic we have an article about, and the lead does not replace the rest of the article. Per WP:LEAD, The lead serves as an introduction to the article and a summary of its most important contents (emphasis added), and on the same page, you find WP:BEGINNING: The first sentence should tell the nonspecialist reader what, or who, the subject is.

Please try to understand that concision has value, especially in the lead. And also in talk pages, by the way: you do not need to reiterate each and every argument each time... Tigraan^{Click here to contact me} 09:28, 13 October 2017 (UTC)

Tigraan OK then why not adopt the simpler definition: "Plasma is one of the four fundamental states of matter, while the others are solid, liquid, and gas." Why is this unsatisfactory? The argument hinges on one premise here that: "The first sentence should tell the nonspecialist reader what, or who, the subject is." It already does?

Secondly, the original version DOES summarise the main article. Taking the section Plasma (physics)#Comparison of plasma and gas phases. "Plasma is often called the fourth state of matter after solid, liquids and gases, despite plasma typically being an ionized gas." Furthermore if you just read the titles through the Main Article, the flow of the text follows the flow of the Introduction. e.g. Degree of ionisation, Temperatures, Plasma potential, Magnetization, Plasmas in astronomy and astrophysics. Have not satisfied this?

Previous Definitions: This article version of 2014 has the same statement.[66] An earlier definition appears in 2006[67], which is far too complex, including another version in 2006[68] by the now topic banned Iantresman[69] All have the issue of being too complex, IMO.

Yet another definition in June 2001 says: "Sometimes called "the fourth state of matter" (besides solid, liquid, and gas), plasma in this context refers to a gas that has been subjected to enough energy to dissociate atoms from their electrons (ionization), producing a cloud of ions and electrons. Because these particles are ionized (charged), the gas behaves in a different fashion than neutral gas in, for instance, the presence of electromagnetic fields."[70]

Evidence suggests Version 3 is historically supported, and that it summarises the topic simply, concise and does meet the Introduction criteria. Arianewiki1 (talk) 23:19, 13 October 2017 (UTC)

Identifying plasma as a state of matter in the WP:LEADSENTENCE seems nearly a given. Listing the other three states of matter in the first sentence seems unnecessary. VQuakr (talk) 00:27, 14 October 2017 (UTC)

Even if it was true that Version 3 is historically supported, consensus can change. Tigraan^{Click here to contact me} 08:38, 16 October 2017 (UTC)

Tigraan When you say "Please try to understand that concision has value, especially in the lead. And also in talk pages, by the way: you do not need to reiterate each and every argument each time...". Perhaps, but when one editor says: Comparing the different versions, it might confuse the discussion that option 3 has three paragraphs, while 1 and 2 only have one. I suggest that the last two paragraphs of option 3 be removed. just to strengthen an incomplete view, it become important to spell out its flaws. Arianewiki1 (talk) 06:37, 14 October 2017 (UTC)

I have genuinely no idea what you tried to write, so I will take a guess that you are complaining that a single paragraph is not enough to introduce the subject.

I do not think anyone suggested to shorten the lead to one paragraph. The diffs I linked to show multiple paragraphs; it is just that because the disagreements focus on the first paragraph, I thought this was the point in discussion and did not deem necessary to clutter the page by including the full lead each time. Tigraan^{Click here to contact me} 08:38, 16 October 2017 (UTC)

Tigraan Simply, the debate is between these two versions[71] Changing the first paragraph have consequences for the rest of the following Introduction text. Thanks. Arianewiki1 (talk) 22:35, 16 October 2017 (UTC)

According to Attic Salt, ""As per sources (Chen, Friedberg) cited in article. Option 3 does not define plasma in first paragraph..." Now I did something naughty and actually read this reference book. According to Option 3, "Plasma is a state of matter in which an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter." Amazingly it says nothing like this in the given reference (pg. 2&3). On pg.3 its definition says : Any ionized gas cannot be called a plasma, of course; there is always some small degree of ionization in any gas. A useful definition is as follows: A plasma is a quasineutral gas of charged and neutral particles which exhibits collective behavior. (My underline)

Now to quote the Introductory text, it defines plasma as (pg.1 Chapter 1) as: "...in the form of an electrified gas with the atoms dissociated into positive ions and negative electrons. This estimate may not be very accurate, but it is certainly a reasonable one in view of the fact that stellar interiors and atmospheres, gaseous nebulae, and much of the interstellar hydrogen are plasmas. In our own neighborhood, as soon as one leaves the earth's atmosphere, one encounters the plasma comprising the Van Allen radiation belts and the solar wind. On the other hand, in our everyday lives encounters with plasmas are limited to a few examples: the flash of a lightning bolt, the soft glow of the Aurora Borealis, the conducting gas inside a fluorescent tube or neon sign, and the slight amount of ionization in a rocket exhaust. It would seem that we live in the I% of the universe in which plasmas do not occur naturally."

So we now learn that the reference does not now state anything like Option 2 at all, and in fact misquotes it entirely. (My earlier 'Formal explanation' actually points this out and simply.) Clearly, the changed text is now wrongly cited, does not say what Attic Salt says, and worst is plainly incorrect. My original version instead actually says this. Arianewiki1 (talk) 11:31, 20 October 2017 (UTC)

• Err... First of all, you are making a logical fallacy. "All X are Y" is different from "all Y are X", so saying "not all ionised gases are plasmas" certainly does not disprove that "plasmas are ionised gases".

Furthermore, from the very passage you cite: A plasma is a quasineutral gas of charged and neutral particles which exhibits collective behavior. How is it "not anything like option 2", which says an ionised gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter? You realize paraphrasing is allowed, and even necessary, right? Tigraan^{Click here to contact me} 12:13, 20 October 2017 (UTC)

There is no logical fallacy here. The definition between an ionised gas and a plasma is that "plasma is a highly ionised gas" whose creation depends density and temperature. (Plasma is really a sub-set of ionised gas.) My point was Option 2 makes no such distinction. You said "However, "plasma is ionised gas" is outright misleading and thus cannot be used.", where you argued to support rejecting Option 1.

My objection is from the associate cite given by Attic Salt in Survey, saying"l "As per sources (Chen, Friedberg) cited in article." for Option 2, is that Chen, Friedberg doesn't say that at all (as shown in the actual quotes from that cite.) Hence me saying: "So we now learn that the reference does not now state anything like Option 2 at all, and in fact misquotes it entirely." That is the point. If Attic Salt wishes this as an option, then there must be cite that supports it. In this case it simply doesn't. Arianewiki1 (talk) 01:22, 22 October 2017 (UTC)

Being a ionised gas, while true, is not the characteristic that defines a plasma. It is just awkward to say that plasmas are ionised gases, but not all ionised gases are plasmas, and by the way a partially ionised gas can be a plasma. What defines a plasma is that long-range electromagnetic interactions matter, or that there is "collective behavior", or that you need magnetohydrodynamics rather than aerodynamics to obtain a decent description - all those three are the same way to say the same thing, and that is what option #2 says. Tigraan^{Click here to contact me} 15:51, 22 October 2017 (UTC)

Thank you, Tigraan, for noting the "collective behaviour": [72]. Arianewiki1, please keep reading! Attic Salt (talk) 12:46, 20 October 2017 (UTC)

In light of the long discussion here, stating "Arianewiki1, please keep reading!" can be construed ad hominem and WP:PA. I've already admitted: "I've taught on the subject, I'm scientifically trained and understand what I'm doing."[73]. Disagree with what I say, fine. But rubbishing someone to reinforce some mute point is a pretty weak shot. Pity. Arianewiki1 (talk) 00:48, 22 October 2017 (UTC)

Two minor niggles on the wording, which could easily be dealt with:

• 2 uses the word "becomes", which is confusing. The sun is made of plasma, and has been that way for millions of years, there's no "becomes" happening there.
• 3 has "Plasma and ionised gases", one singular and one plural. I can think of no reason for that.

Maproom (talk) 07:10, 25 October 2017 (UTC)

It looks like the request for comment expired. Option 2 is preferred in the survey. Since the other options don't have much support, perhaps we can adopt 2, otherwise perhaps we should reopen the request for comment. The latter might also call some additional involvement in the article as a whole, which I think would be good thing. We could also insert option 2 AND reopen the request for comment. Attic Salt (talk) 14:05, 10 November 2017 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Amakuru, you have closed this request for comment, saying "there is a rough consensus for version 2, and something like that has already been inserted into the article". And yet what is "already inserted into the article" is, essentially, version 1, which only received the support of one editor. This is a technical article, and technical distinctions are important. I invite you to reconsider your summary and closure of the request for comment. Thank you, Attic Salt (talk) 13:33, 17 November 2017 (UTC)

@Attic Salt: thanks for pointing this out. I have now replaced the opening paragraph as per the result above, and amended my close text to clarify this. Thanks  — Amakuru (talk) 14:42, 20 November 2017 (UTC)

Incorrect statement of fact.

"The positive charge in ions is achieved by stripping away electrons from atomic nuclei." States the current article. I believe this is incorrect, there are no electrons in atomic nuclei. "Nucleon" Wikipedia" "In chemistry and physics, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus." AnnaComnemna (talk) 15:55, 30 November 2017 (UTC)

• There is indeed no electron in the nucleus, but I do not think the sentence implies the opposite. I would read the sentence more naturally as "taking electrons away from the vicinity of the nuclei" rather than "taking electrons out of the nuclei" - but I know what an atomic nucleus is and I am no native English speaker, so maybe the sentence is misleading or incorrect and I do not realize it. Tigraan^{Click here to contact me} 18:21, 30 November 2017 (UTC)

"From" in this context seems reasonable. It doesn't imply electrons are part of the nucleus. VQuakr (talk) 19:25, 30 November 2017 (UTC)

I would have said "disassociate" (or "disassociated electrons"), though of "strip away from" is also standard terminology. Perhaps "strip away from their associated atomic nuclei"? Attic Salt (talk) 19:32, 30 November 2017 (UTC)

I was the one who wrote. It is a simplified statement that is similar to other cited texts. Again it relates to the degree of ionisation, where the electrons exist as sea but there continues some interaction between the the remaining electrons and the nuclei. Disassociate cannot be used as in chemistry this refers to interchanges between ionic states occurring in liquid solutions. The later statement explains this: This also can be accompanied by the dissociation of molecular bonds, though this process is distinctly different from chemical processes of ion interactions in liquids or the behavior of ions existing in metals.

Considering now the recent consensus change in the first sentence has mostly destroyed the original logical flow within the article's introduction. I.e. The alleged characteristics are of a plasma in "definition of a plasma" responding to magnetic fields and being highly conductive are not actually characteristics. For me, it is important that the third paragraph is not broken. This because it properly defines the needed characteristics and environmental conditions to create a plasma state but also differentiating similar kinds of conditions of the other states. Its current third paragraph structure, considering the poor state this once was, is simple, informative and correct. Arianewiki1 (talk) 23:36, 30 November 2017 (UTC)

For example, Chen, Intro to Plasma Physics, page 1: [74].

Thank you. I have read and considered your comments. I am not changing the article, or my opinion. AnnaComnemna (talk) 02:42, 18 December 2017 (UTC)

Lede

I respect the Rfc, such as it was, which is why I neither added nor subtracted any information, please compare versions. The 3rd sentence does not make any sense; "Unlike the other three states of solid, liquid, and gas, plasma does...". Fixing that (and cleaning up double spaces) is the only difference between versions. 50.64.119.38 (talk) 01:42, 14 January 2018 (UTC)

Wording question

Under the heading Thermal vs. Non-Thermal Plasmas, there is a sentence: "Non-thermal plasmas on the other hand have the ions and neutrals at a much lower temperature..."

I don't think "neutrals" is correct. However, I don't know if the intended word was "neutrons" or "neclei." Kirby777 (talk) 21:58, 24 May 2015 (UTC)Kirby777, 5-24-15 at 5:00 pm CST.

Very late answer but "neutrals" is correct, it is a common wording in plasma physics referring in a simpler way to "neutral heavy species", i.e. atoms and molecules. – Tokamac (talk) 15:54, 7 April 2018 (UTC)

Requested move 15 December 2018

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this section.

The result of the move request was: not moved. Calidum 19:49, 22 December 2018 (UTC)

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Plasma (physics) → Plasma – When users are looking for blood plasma and plasma they now need to go to a disambiguation page, which is inefficient for all readers. If we were to move this page to Plasma, readers looking for this page would not need to go to a disambiguation page, users looking for blood plasma could go though a {{for}} template, and everyone else could go though the disambiguation page. It also makes sense to have to move this page to Plasma because Blood plasma only has plasma in the name, where as the name of this page is just "Plasma". Plasma (physics) received 89,020 page views in the past 30 days with blood plasma only receiving 37,601, making this page the WP:PRIMARYTOPIC. – BrandonXLF ^(t@lk) 15:46, 15 December 2018 (UTC)

• Oppose there is no primary topic for this title; Plasma is rightly a disambiguation page. If Blood plasma were the only usage of the word, it would be located at "Plasma"; use of non-parenthetical disambiguation is irrelevant to your move proposal. Move proposal doesn't make clear what has changed since this was last strongly rejected, most recently on 10 March 2016. VQuakr (talk) 19:10, 15 December 2018 (UTC)

• VQuakr, What has changed is Plasma receives significantly more page views then Blood plasma. As well, the move would make it easier to get to here without effecting how many clicks it takes to get to Blood plasma. – BrandonXLF ^(t@lk) 00:26, 16 December 2018 (UTC)

That's not new; it was considered in the previous move discussion, too. "Plasma" can mean many things as demonstrated by the lengthy disambiguation page; the fact that the plurality visit here doesn't make it such a primary topic that the page move is warranted. VQuakr (talk) 00:35, 16 December 2018 (UTC)

• Oppose. Plasma is an ancient word, associated with ancient concepts predating and unrelated to the physics term. Blood plasma is a strong example of this. However, part of the rationale is correct, "When users are looking for blood plasma and plasma they now need to go to a disambiguation page, which is inefficient for all readers". This is the fault of WP:MALPACED, which somebody made up one day for no good reason. Repudiate MALPALCED, move Plasma to Plasma (disambiguation), and leave the redirect Plasma --> Plasma (disambiguation). There is no primary topic, and disambiguation pages should not be ambiguously titled. With the disambiguation page precisely recognizably titled, people looking for the physics or blood or other plasma topic will know to look just a line or two further and not be misled into the dab page. --SmokeyJoe (talk) 06:16, 16 December 2018 (UTC)

@SmokeyJoe: WP:MALPLACED is solidly grounded on WP:DABNAME: "when a disambiguation page exists at the ambiguous term, there should also be a redirect to it from the "(disambiguation)" title". Narky Blert (talk) 13:31, 19 December 2018 (UTC)

Same thing, both built in sand and not a good idea. —SmokeyJoe (talk) 20:54, 19 December 2018 (UTC)

Full-time DABfixers have seen that idea before, and we treat it with utter horror. Come back to us when you've done some serious DABfixing, and we might give more weight to your opinion. Narky Blert (talk) 01:14, 20 December 2018 (UTC)

How about you give me some substance now? Dabfixing appears to be an endless task of cleaning up then water pooling from a broken pipe. It won’t fix every problem, but if *all* DAB pages were suffixed “(disambiguation)”, then ordinary editors would not be mistakenly linking to them. They might continue to link to the redirect pages, but would fixing that be worse. More important though is the reader, which includes many editors, knowing that a page title is the title of a disambiguation page, a simple compliance with WP:PRECISE, also RECOGNISABILITY, and maybe it could lead to CONSISTENCY for DAB page titles. We have given this a lot of talk at WT:AT, and WT:D, and Talk:New York, and the only counterpoint so far that I remember was DB2414’s This would be a huge change to implement. It doesn’t need global implementation. Why not fix this problem here today? Explain the “utter horror”, is it more than just a radical change to a never considered primordial practice? —SmokeyJoe (talk) 02:04, 20 December 2018 (UTC)

It would break User:DPL bot, the DABfixer's main tool. BD2414, who has made over 1.2M edits, and who has a record going back to 2009 of often fixing several thousand links to DAB pages a month, knows whereof he speaks. Narky Blert (talk) 16:48, 21 December 2018 (UTC)

• Oppose. Blood plasma is at least as significant a meaning, and more widely known. Narky Blert (talk) 13:27, 19 December 2018 (UTC)
• Oppose as there is no primary here, but I suggest moving the page to Plasma (state of matter). Rreagan007 (talk) 00:36, 22 December 2018 (UTC)

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The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Language unclear

I am writing this because my Wiki account does not yet have the privileges allowing me to edit parts of this article.

Under "Properties and Parameters --> Definition" there are 3 factors listed as requirements that the properties of a medium must fulfill in order for the medium to be classified as a plasma. Factor # 2 says the Debye screening length must be sufficiently small relative to the size dimensions of the total medium. I am aware that this aspect can be explained in more mathematical detail but that the author chooses (for good reasons) not to do so.

The next part is what I feel needs a more precise formulation: The author explains that the Debye screening length being sufficiently small relative to the total medium size means that bulk interactions inside the plasma are "more important" than those at its edges.

Under "more important" I understand that these interactions make the largest contributions to determining the overall behavior of the plasma, i.e. they have the most influence in developing the statistical averages of various physical properties of the plasma.

Assuming I have interpreted this correctly, I would like to note that it took more time than necessary to arrive at this conclusion, simply because "more important" is a formulation of subjective perception and I could not see right away what it was supposed to be telling me about the objective, quantifiable nature of the relationship between bulk interactions and plasma behavior.

I therefore suggest reformulating and replacing "more important" with something that better shows the objective role bulk interactions play in the quantitative plasma model being presented here. AD203 (talk) 19:31, 13 July 2019 (UTC)

Need to articulate

I'm a scientific layperson and though I am literate I find some of this opening body in need of explanation.

"Plasma can be artificially generated by heating or subjecting a neutral gas to a strong electromagnetic field to the point where an ionized gaseous substance becomes increasingly electrically conductive, and long-range electromagnetic fields dominate the behaviour of the matter." I feel this needs some better wording, why should the general reader know anything about EM fields?

I don't intend to criticize the writing of this article, I am concerned only about the general readership of it. In the next paragraph, "Based on the surrounding environmental temperature and density [...]" of what? It does not seem to explain it very well. I am not a science student but I feel this could be bettered by a more effective writing.

I hope I don't come across as a cunt my friends. Pardon me. Thank you for your work fellow wikians.

Dudanotak (talk) 09:21, 22 September 2019 (UTC)

Thanks for your comments and criticisms. You are correct that the lead of an article should be as simple and clear as possible, so that readers may gain at least some idea of what a topic like plasma physics is about. While we cannot provide in-depth explanations in the lead due to space considerations, I have tried to rewrite the unclear passages with a little more clarity. See if it helped. --{{u|Mark viking}} {Talk} 18:04, 22 September 2019 (UTC)